I think he's more just overwhelmed by the expectations and pressure put on him now, and I think everyone telling him to finish the books before he dies really pissed him off in a visceral way and made writing them feel really uncomfortable. I could see that sentiment, that he owes the ending of this series to the world and that he needs to do it before he dies, making writing the rest of the series feel like a chore to meet the demands of others instead of as an outlet for his creativity and also a race against his own mortality. That would feel terrible. I can understand why he'd ignore the ending and just focus on writing short stories nobody asked for instead. Keep the creative outlet, but shun the pressure and the death clock ticking in your ear with every page completed.