I would as other pp say sit and talk genuinely to him about the consequences. He is being selfish and allowing himself to destroy his relationship with them rather than seek help.
I say this from a place 40 years on. My df is most definitely (and I have several reasons to know this and not to say it lightly ) ASD but at 75 and growing up in Wales no way would it have been recognised so he got no support. He is also off the charts intelligent in some things and was professionally successful. He was exactly the same way. I know , now cerbrelly at 40 that he loves me and dsis more than we could imagine. Hes petrified of anything happening to us. However I didn't hear a nice word from him ever. He permanently criticised us , it led to horrendous self esteem issues for both of us. Nothing was ever good enough (even we knew that he thought he was motivating us to push further , do more , all it did was tell us we were never good enough)
Finally in his 70's he started to realise we never came home, we never rung him, he realise done day he didn't know what I did for a living. The trouble is , to be honest , it's too late. No amount of being nice now (he still struggles as he genuinely doesnt understand empathy but he tries as if he has learnt by rote and studied it....he probably has).
Nothing can remove that at 15 he told me I looked common. Or that he put up with me under sufferance. He will never be able to have the relationship with me he wants because even if I wanted to he eroded it , with every little nasty comment, every pull of the face , every disappointed sigh. By the time I reached my twenties that relationship was dead in the water.
At 40? It couldn't be brought back if I tried.
Remind your DH, there isn't always time to change things. There will be a point of no turning back and it's far far closer than he thinks .