Yeah, DD went off on me a couple of times and did apologize after explanations and apologies on my part. Anyway, I am presuming that he's paid a hell of a lot of dues along the way and led an interesting life. Part of that life may be catching up with his body now and he doesn't want to "go quietly into the night."
Also, it's good to remember that autism, like most conditions, is a spectrum. Just as everyone's cancer or cold is different so is the autism that affects us. You may be a .25 in facial recognition, while I may be a .39, but we both have autism. I just cut him some slack and try to remember to put LOL behind any funny posts directed at him so he'll know I'm fooling around.