I haven’t met the kid yet but I’m told that his symptoms are not too severe. My thought is that wood turning might be something he could do. A lot can be done with one hand holding the tool steadied by the tool rest and the other holding the handle against the body.
I saw that one form of therapy is something called bimanual training. These are activities where both hands must work in concert. Wikipedia listed as example holding a marker in one hand and a pad of paper in the other. Well, heck, most stuff in the shop is pretty bimanual.
I’ll know a lot more when I meet the kid and find out what he would like to do. I can’t offer up any expertise other than my patient attention.
I’m open to suggestions…