The guy did step forward though, it was small, but he did. The riders are also going A LOT faster than they would be going when climbing.The guy didn't step forward: he was encroaching on the riders' line a lot less than spectators in the mountains. It is the riders' responsibility to look ahead and remain more than an am's length from the spectators. If they do that and the spectators still manage to hit them, then it is the spectator's fault, but that is not what happened here.
Watch the white shoes and trousers at 39 seconds, and then tell me that he did not step back...The guy did step forward though, it was small, but he did.