some kid at some point is going to make a joke/laugh at him (or even a teacher), this is certain to happen. Well what will he do? I think it's going to depend on his personality, one of my classmates used to stutter like me, he was outgoing, social and not giving it a thought, while I was the complete opposite, I hated every single minute in school 😂 I don't know if it still affects my personality, but god when I pass next to my school on my to work every morning and hear the sounds, my heart races like I'm still sitting in that classroom worrying if I'm going to get picked to read out loud. Keeping him at home for another year is a risky decision .. what if his stutter doesn't go away? It's the safe thing to do, but it could lead to nothing after all. Then on the other hand, I can think of many ways where things could go down hill if other kids start to tease him. Perhaps you could just test his personality now, find him an activity where he will have to talk to other kids, and see how things go.