I'll add that I think some kids are more comfortable with the role of "expert" than others. The danger for a 9yo is that he won't know an answer, and then his position in the group might feel jeopardized, especially if perfectionism is an issue for him. That fear might be eliciting the sorts of insecurity that you're seeing.
If he has chances to be wrong in front of his friends and still be okay with that, it might help. But he'd have to be okay with it. A meltdown would be bad. But if he can be imperfect in front of his friends, that's probably a good sign that he's doing okay.
There's a fine line between liking to feel useful and feeling pressured. Some GT kids are natural teachers who love to share what they know. Others feel pushed to be perfect. I think it really comes down to how comfortable he is in that role.
