elfie, when things have died down a bit, make him get his blood checked for hepatitis and aids, if he got the guys blood on him. i doubt he was wearing gloves at the time.
i don't mean to be sensational about this or scare you; just being cautious. lemme 'splain.
several years ago, i was leaving church a little early (after communion, before the last set of calisthenics
) and was followed out the door by a little old italian lady. as i got to the bottom of the granite steps, i heard her fall and come tumbling down behind me. she face planted, and tore most of her nose off her face. i did as your son did, pushing it back into place and keeping pressure on it until help arrived. (i gotta stop going to church and coming home all bloody. it freaks out the neighbors)
i happened to have a checkup the next day, and related the story to my doctor, who made me get tested, especially for hep.
now, she was a little old lady, so i wasn't worried, but ya never know.
so, just as a precaution, get him tested.
btw, i was "clean", but now i get these strange urges to cook whole meals for my family at 4am, and i can give a really good evil eye.