He didn't "flip off" the crowd. Look up "flip off" on the net and be enlightened.
When a team or player overcomes the screaming fans, some abusive, he has a right to acknowledge the accomplishment towards those that have been screaming in his ear. It's a pretty thin skinned group that can yell, some abusively, for 3.5 hours and then be offended when a player looks back at the crowd and puts his finger to his mouth implying that he has overcome the hostility.
