If you try to force a kid to stay at the given pace they won't be challenged and just fizzle out in most cases. Most genius tier kids that didn't just give up by graduation just never learn how to properly apply effort and make the struggles much harder with whatever comes next and where your worries about having to perform highly all the time actually fits and can and will crush people. Ideally the parents of the kids will be able to still help him socialize outside of the classroom as well to help them develop those skills too, no matter what approach you take a kid will miss out on something. there's an endless amount of knowledge that can be pursued no matter how quick they absorb it, but as far as social development it just means that theirs will be unique, just like everyone's