Seems to be the way with these things, it was the same last year when Cav was DQ'd from the stage when he leant on Thor Hushovd as the barriers narrowed. The correct response to that (IMO) would have been to relegate him to the last place in that bunch, as it was it was that one decision which cost him the green jersey. In fact Hushovd was equally guilty for almost forcing him into the barriers!
That sort of argy bargy happens in sprints all the time, I've seen worse than that. 🙁
I don't get the Cav slagging that goes on here though, he's a really nice guy in person. Actually quite quiet.