Just get a documentary about aspergers put it on and when you see stuff he does just say: hey that looks like something you do, that too, that also. etc etc.

it's unlikely that he doesn't suspect it himself because if he's educated he has probably read a lot of philosophy and other books trying to figure himself out and knows himself to be different or autistic.

I'm 22 but i knew i was different from like 12 but i'm also able to be really social if i want to so people won't notice.
makes life difficult and lonely a lot of the time, not cause i can't get girlfriends or friends just nobody relates to you, nobody talks about the same things as you do.