I took college classes from 9 to 13, then my parents pulled me out entirely. There were good and bad aspects to my path. At 13, actual graduate math classes were a bit over my head, and I felt a lot of pressure and feelings of failure because I couldn't quite hack them. Also, being isolated was hard, and it wasn't until I came back to grad school at 22 that I felt I developed my social skills properly. But being allowed to focus on intellectual pursuits was really nice in a way, and I actually look back on that fondly. Now I have my PhD and work for Google, and I do geeky things for fun. As one example, I'm noodling on keyboards, and, being me, I'm writing a DX7 synthesizer emulator. Most people consider the math of it to be impenetrably difficult, but, I'm like, "oh, _Bessel_ functions, I can dig that shit!"
I hope he does well and finds a path that makes him happy. One thing my parents did was keep me out of the newspapers (and off the front page of Slashdot, although we didn't have that then). I'm not sure whether that was entirely good or bad - publicity is valuable coin in today's society :)