I love how everybody is like "this dude is fucking scum" without knowing if the girl was some sort of crazy woman or not. Just because she's pretty damn small, it doesn't mean she can't use violence. And I don't think the guy intended to punch her into a coma. Then again I don't think punching around is the best way to go, but without knowing how everything went, I'd rather not call him scum or a douche or anything.
PS. I personally would not punch a lady. But when a "lady" comes by and tries to physically hurt me, she stops being one, and just becomes a 'real man' trying to use physical violence, and then.. yeah, I don't care if I punch her (if I can't just hold her hands, that is).