I think Cav was following Demare's wheel and had the right to take the small gap through past Sagan next to the barriers. The problem lay in Sagan not knowing Cav was coming so drifting off his initial racing line to take Demare's wheel which then forced Cav into the barriers. Moving away from your racing line is the illegal manoeuvre in this case.
I think it would have been correct to dock Sagan 80 points, fine him and put him back to last place (etc) as is commonplace but a DQ was over the top. Sagan's right elbow flicked out as did the left knee which anyone who has raced before knows is a fast way of trying to regain balance. It was just unfortunate to see Cav fall as he was trapped in.
It's all a conspiracy to try and get the French to actually win something
