Maybe she was alright afterwards, but depending where he hit, he could have done some damage to her, he just got lucky and didn't. The crowd was hardly agitated, they were shocked at his actions to be sure, but all they did was record and watch, and one or two even helped the officer by pulling back the other girl while the officer focused on the one who pushed him. You're talking as if the girl began punching and kicking him, a shove from a teenage girl does not warrant a punch to the face. He was doing his job, but he was wrong in the way he went about it. Don't forget, the police are public servants, it is our position to call them out on it if they're doing their job incorrectly. Lord knows police higher ups won't do anything, all they ever do is cover it up and protect their officers. The 'blue code of silence', as it were.