Surprised there doesn't seem to be more in the cycling press about this if as I understand it someone pulled him back by his saddle. There would be uproar if it happened to say Froome on the TdF, so is it just an accepted part of racing for young up and coming riders?
Pretty shameful if it happened, and no it's not an accepted part of it, however to take it further there needs to be evidence - maybe it wasn't seen by cameras etc.
Not clear whether he is accusing another rider of deliberate infringement - the term rider error is used. Remember Sean Yates losing the Yellow Jersey years ago cos a rivals team mate grabbed his shirt in an intermediate sprint. By the way Yates took it you got the impression it was a common tactic, and like other forms of cheating it was kept within the peleton.