excellent....I am very impressed. And i do think as things get harder, he'll sign more......and I think actually you're dead on with your observation that he's expanding a lot of energy on oral/aural bit of language......you could make it a game. I clearly remember being that age and thinking " Oh i don't "need' ASL b/c i can talk.
I didn't understand that ASL could be used when my hearing aid was broken or in difficult listening situtions.
Maybe go the superhero route.....say "hey you have a superpower...you can turn off your hearing and we have this very cool secret language we can usetogehter!"
