Re: New to boxing, again.
As a boxer myself I can understand your concern. From what it sounds, your son is in great shape, and looks like he'll find his fit in boxing. Go ahead, you and your boy check out that gym. Makesure it's not school of hard knocks, also keep in mind that no boxing gym is the same, some are more physical, fundamental, and breath-taking than others. Alotta people switch gyms to find one that suits them, I'm just try'n to say that you should check a few places out to find out what fits your son.
I think it's a good Idea for your son to see what boxing's really about. Even though your son has a head start over most people, the coach will probably go over the fundamentals with him, (Footwork, Defence, Offence, Range, Timing, the works) and only after the coach thinks their student's are ready, that they put them in the ring for sparring. Remember sparring isn't about bust'n the other guy's nose and doin him in/vice-versa, its about learning the skills at hand. So give it a try see how it goes and as long as you are willing to be supportive, then give it shot.
Regards'n Good Luck,
If you hear a voice within you saying that I am not a painter, then by all means paint and that voice will be silenced.