Interesting. I'm deaf myself and would love to be an pilot some day sometimes. My biggest concern is tuning the engine but that's not the point of this thread. I'd say that
ASK him what he would like to do, it's only fair. You said he was an excellent pilot, if he is then there should not be any issues. I do like the idea of a spotter with him if there's anybody around available/willing to do that.. If he's alone, I don't see a problem with that.. Like is aid before, just ask him
I'd much rather someone to ask me for ideas, about my past than rather setting up rules and stuff JUST FOR ME before asking me for my feedback, that's just silly.