Well here is my unsolicited take. The slugger is left handed and positioned himself where he could effectively Knock the schit out of the skinny jeans guy. He knew something might happen and he put himself in a favorable position to hit the guy hard on the jaw. The skinny jeans guy was/is a dumbass. Would I have hit him? Yes. Would I have cared about my possible legal issues? No. Where I live in Johnson county I doubt I would have had to go down town and explain what happened.
This, because you wouldn't have expected him to keel over like that. Neither did the guy that tapped him.