Since when is a bitch slap equal to a beating? You musy be a huge pussy if you think slapping a slut in a bar is horrifyingly reprehensible. I've never heard of a person going to jail for slapping anyone. A slap is used to prove a point and teach a lesson. A beating is used to satisfya mentally sick person's thirst for violence and dominance to an inhumane extent. A slap is an exertion of dominance healthy for both parties.
And why is it about impressing a girl? This is about teaching a skank to repect other people, or else be disrespected. She hit him first. Like Malcolm X put it (sorry for paraphrasing you in PL, Malcolm) an act of self-defense is not violence, it's intelligence. By walking away like a little bitch, this guy showed he feels at least a bit guilty for whatever happened, which is NOT the message he wants to send.
This post makes you look like an asshole. Saying skank and slut just make you look like a masogonistic prick who would probably be an abusive partner in a relationship. It's okay to demand respect and assert dominance, but there are other/better way to do it than through physical altercations.
I agree that slapping someone is far from a beating, but you shouldn't put your hands on a woman. Period.
If he needed to restrain her in an act of self defense then fine, but he doesn't need to fight back. The bouncer took care of the situation as he should have...
BTW, you said that no one is going to jail for slapping someone... I guarantee you that if you slapped a woman in the middle of a bar, the police would come and the man would be arrested... It sucks but typically in a domestic violence case, the man is going to go down even if the woman attacked him first... and even if he "only" responded with a slap