Be honest, do you think he's worked on them at all since the show started?
He may have done a chapter, maybe two since then? That's probably it, though.
He has no intention of finishing, especially now that the show is done and people are left with negativity surrounding the ending. It's the worst possible situation for him, because even if he wanted to finish the books there's just no way he can do it.
IMO, the best thing he can do is acknowledge this, and draw a line in it. Either hand it off to a protégé or writer friend that is happy to continue the story, or outright say that ASOIAF is done.
Haha, I thought I was the only one!
I started doing it to annoy my wife, but now I still do it, and it's taking considerable concentration to not dab when I sneeze.