This is your theory. Some people also go out of the way to judge a rider they do not like. It goes both ways, and there is no way we can escape our biases unless we are completely dispassionate about the riders. Luckily, this is not the case, as the debate would be potentially boring with only one correct opinion. Cycling is not a black and white sport - that is what makes it so great. Let's never pretend it is black and white for if we do, the magic will be lost.
I actually (after a couple of initial posts poking fun at myself) criticised the Sagan DQ in 2017 and thought the original relegation was sufficient - and my post above was not about Sagan the rider but more about the reaction it drew. In the wake of Groenewegen/Jakobsen, there was a lot of talk that the UCI was partly culpable because they never punished such moves unless there was a crash, and that they should punish moves like that even if there wasn't a crash, to prevent incidents like that happening again. But we've seen a lot of people criticising them punishing somebody for precisely that violation despite there not being a crash - which was apparently what we wanted. The problem is, judging such moves when there isn't an incident becomes far more of a judgement call; at the same time judging solely on outcome is fraught with danger as people could be severely injured by an innocuous incident, or walk unscathed from a brutal incident.
And let's not pretend personal opinions don't impact our views on these incidents. I mean, Mark Renshaw committed two relegation violations within about three seconds back in 2010, but a lot of people thought it unfair to disqualify him. Yet what were the commissaires to do? He's a leadout man, he doesn't care about being relegated to the back of his group and his sprinter just won the stage. You can't punish Cavendish for Renshaw's actions, because
he's done nothing wrong. And Renshaw has committed two offences in quick succession. It was perhaps a difficult one because usually a first offence will merit a relegation and a warning but continued violation will be an expulsion, but Renshaw didn't have time to be warned for his first violation before committing the second. If you like, it was like a footballer committing a yellow card-worthy foul, but then committing a second one while the ref was playing advantage for the first one.