So, he would be offended if someone was checking to see if he wanted something specific
That's not what he said; I didn't think it was how I described it. He was offended because someone said, "What should I get you for Christmas?" Or "what do you want" in a way that indicated they wanted him to name one specific item.
or had any request to make sure they got him something he wanted
Again, a restatement that misrepresents the subtleties here.
But then, you guys aren't related to him, so it doesn't really matter what you think of him
There seems to be a disconnect there.
People are funny that way--lots of us are inconsistent.
It doesn't seem that inconsistent to me, that what he doesn't want is for someone to pawn off the "work" of picking a present on him--that the underlying message of that is not "I don't know you as well as we both wish I did," but rather, "I can't be bothered." The first is not nearly as hurtful as the second.
I don't even know what to buy my husband.
I don't either. My son's philosophy, I think, would be that I should give myself some time to stop and think, and then just take a stab at it. But I think my son would say that I shouldn't go to my husband and ask him to name something that I can wrap up and put under the tree.