“You swore at him and were aggressive and hostile and you threatened him. The victim was quite blameless. He went to apologise and touch the boy in a gesture of conciliation, but you took exception and struck him in the mouth.”
This is a terrible tragedy. I have often remarked that in today’s society you are better off not trying to touch children of people you don’t know. I personally find it irritating when strangers try to ruffle my son’s hair or touch him in some other fashion. Boundaries are important.
Still, what this man did was wrong. There was no need to hit the other man over a simple accident.