Unless I truly believe that I am going to be very seriously injured, which from everything you said that guy didn't, there is no way in hell I'd beat up a minor. I don't give a damn about the workplace or even the kid, the parents can decide to press charges against the kids wishes and I would be boned. Hell look at what is happening these days, that shit could come back to haunt you a decade later and the situation would be largely irrelevant. "30 year old man beats 15 year old child" would be all anyone heard.