Adult males can be found in a lot of places.

When I was his age I was pretty much independent. I went to lit club meetings, computer club meetings, astronomy club meetings, rifle club, etc on my own. I found a great mentor when I was 14 in computers.

You might be able to channel an interest of his??

Martial Arts is good, but most do not give you the underlying physical fitness. Most are not design to win a real fight. Krav is the best, but, the adult male presence will be there in any case.