There have been a good few crashes that can be used as precedents here, the problem is that it borrows elements from all of them.
I can't imagine going on as a rider in this race while Jakobsen is fighting for his life.
Some people may withdraw, but most won't. Maybe Fabio's teammates will feel uncomfortable with it. I remember stories of Fabian Wegmann (at least I believe it was him) shacking down on the floor of another room because he was rooming with Wouter Weylandt in the 2011 Giro and didn't want to be alone the night before the parade stage. Matteo Pelucchi left the sport for months to practically live at the hospital while his fiancée recovered from her career-ending injury that left her paralysed from the waist down. These things can affect people. But at the same time, the péloton raced on in the 2011 Tour de Suisse when Juan Mauricio Soler was facing potential brain surgery; they raced on in San Luís after Malori's horrific injury. It's a strange sport like that. It's one of the most respectful, and simultaneously one of the strangest in its reactions to the hazards of the road. The péloton unites when one of its number falls; we've seen a few heart-breaking parades in our time, and there are things that I remember vividly about the way the sport honours its fallen. Tomasz Marczynski pinning Lambrecht's race number to his heart, Leopard Trek letting Tyler Farrar join the parade as they crossed the line, Lance Armstrong's finest career moment, winning a 1995 Tour stage and pointing to the heavens for Fabio Casartelli. To this day I will always have a soft spot for Vasil Kiryienka regardless of years as part of the race-stifling apparatus at Sky, because of his 2011 Giro stage win honouring Xavi Tondó - but simultaneously I still resent that his pride meant he put his sunglasses on at the line so the photos wouldn't show his tears.
It's a strange paradox of a sport. It will go to these lengths to honour its fallen comrades, and yet, a day of mourning is taken, and then it's back to business, save for the occasional sop to safety like the cancellation of Monte Crostis in 2011 after some misleading photographs and with an understandably nervy péloton made it perceived to be necessary. It's almost like it's Formula 1 in the 1960s, when Jackie Stewart was being mocked and laughed at as a coward for wanting to improve safety, because it "wouldn't be racing" if it were neutered for safety, as if Stirling Moss being told by his co-driver at a driver change in the 24h Spa to "watch out for body parts at the Masta Kink" and finding not some broken bodywork but dismembered arms and legs decorating the road was an acceptable state of affairs. But some of the worst incidents were just sheer stupidity. One of the saddest things I've ever seen, and certainly among the hardest to watch, is the footage from the 1973 Dutch Grand Prix, of Roger Williamson trapped upside down in his burning car, with David Purley getting out of his car and running across the track to save his friend. The marshals have no flame-retardant clothing and only one fire extinguisher, so they can't go close to the car and he is trying to turn it over, trying to put the fire out, trying to save the day with this woefully inadequate equipment while the marshals can only watch on helpless until the situation becomes hopeless and they have to lead Purley away to stop him from risking his own life. You know what the race organisers did? They continued under a local yellow flag, which meant the ambulance and fire engine couldn't get to the scene until far too late because there were still cars going at race pace. By the time they got there the car was a burnt out wreck and Williamson was long since asphyxiated. They flipped the car the right way up, rolled it out of the way, put a blanket over it and continued the race. With Williamson's corpse still in it.
Nowadays, that kind of level of organisatorial irresponsibility is almost impossible to fathom in any sport (and thankfully so). Even when the organisers tempt fate to the most ridiculous of levels (see Dan Wheldon's fateful accident, an enormous pileup at high speed which Dario Franchitti described as being "like driving through the opening scene of Terminator"). There is the occasional example in cycling of how completely brain-dead a race organiser can be; if you recall a few years ago the organisers of the Vuelta al País Vasco saw a terrible crash on stage 1 there, in Bilbao, where they held the same finish as had been used in the 2011 Vuelta, only they didn't have the same level of barriers and didn't realise until the day that with all the cars removed, there were vertical metal posts in the road, and their solution was to put traffic cones on top of them as if that would suddenly cause riders to not move around in the sprint. Sheer idiocy. Shornig up the structures with bricks goes in the same category - whilst it makes some logical sense, there's a good reason that solution is seldom used: because when it comes to a situation like a crash - which is hardly a rarity - it takes an already dangerous situation and makes it worse.
When it comes to Groenewegen, you know, these things often police themselves in the long run. He's going to feel terrible about it, and obviously there are some elements of judging the outcome rather than the incident. People were wary of Cavendish for a long time after his string of 2010 crashes. Sagan's DQ in the Tour a few years ago was influenced by previous, which led to the perceived overreaction from the commissaires (notwithstanding that in both cases there was a contingent who seemed to go out of their way to find the offender blameless just because they liked them, the decision was controversial regardless - although one wonders if he would have received the same support, and the decision the same backlash, had Cavendish been as badly injured as Jakobsen has been here, though this move by Groenewegen at least
feels somewhat worse). And then there are people like Romain Feillu, Nacer Bouhanni and Roberto Ferrari who get pigeonholed as dangerous sprinters, for whatever reason (for some it's numerous infractions, for others it's a single, but particularly egregious and high-profile, incident). Nobody will want to give Groenewegen their wheel, people will tread carefully around him, he will find himself boxed in and also particularly unpopular with the people that police the leadouts and throw their weight around when the camera isn't on them, like Mark Renshaw used to.
Is this particular incident as bad as the Theo Bos/Daryl Impey incident in Turkey? Groenewegen was no doubt reckless, and acting with no regard to the safety of himself or anybody around him... but simultaneously at least it was a racing incident. An incident that could have - should have - been avoided, but changing lanes in a sprint is not as immediately egregious as
literally (actually using that correctly) wrestling a guy off their bike at 70km/h+. Hell, people like Djamolidine Abdoujaparov have become folk heroes for sprints of that kind. It doesn't usually matter to the commissaires if you change lanes if you're faster than anybody else - Cav never caused issues doing it until he had no form and he wasn't over a bike length faster than anybody else, for example - and so in general sprinting on the crab is never called out unless either an official protest is lodged or an incident occurs, which given the kind of speeds talked about in a sprint usually means high risk of injury. However as hrotha pointed out, the fact that this offence is practically never punished unless somebody gets hurt means that sprinters are willing to take their chances, because they won't get punished unless the other guy fails to back down, or they lose control, and here you had multiple things go wrong in those respects, combined with an irresponsible decision by the race organiser, that exacerbated the problem. You can punish Groenewegen for irregular sprinting - indeed he has been - and you can perhaps punish him further for repeat offending if that is an issue (I don't feel that they can do that unless they've actually punished him before, though; if he's been sprinting on the crab a lot but this is the first time he's been called on it, then he would be within his right to argue that it is unfair to punish him as a repeat offender for something he would have felt was considered acceptable before because he wasn't being punished. But punishing based on outcome is fraught with issues because the race organisers are also to a large degree responsible for the grave outcome here, because while Groenewegen undoubtedly caused an avoidable crash, a dangerous run-in and the use of bricks by the organisers also carry a huge responsibility for the injuries sustained and those should not be pinned purely on Groenewegen's shoulders. País Vasco was put on final warning following the traffic cone incident and the UCI demanded better safety guarantees and standards in the wake of it. There's no way the same threat should not be directed at Czesław Lang and his team here.