It made sense in the mind of people who have seen it done many, many times before. Was it your preferred tactic, obviously not, but sending a rider on the offence when the last dom is done is just textbook.
Regaining control of the situation, so you don't have to close down attacks or pace hard with leading riders, is this not normal tactics? Now, group two dynamics made this look much worse for people like you that don't agree, I get that.
What if Roglic was feeling frisky and started his stomp a little early that day, at 1km even and put in 30sec on the others with bonus that would be fine right? Or do we not agree that he would have attacked at the top?
As I see it, Jonas attacking was fine if you are all in for the team, if he wins, great, if not, Roglic probably does. That's a good team situation. Now butt-hurt fans and possibly Roglic (don't actually know this for sure) that is a different beast.