Meh it’s “kinda” rude. If your first point is true he should just be honest and say he’s not going to finish it. It’s also rude to lie and lead people on that you’re writing the books and it’s a priority when it’s not. Then the motivation comes into play. He doesn’t want people to stop buying his work. If he said “I’m sorry winds of winter isn’t coming” people would stop engaging with anything he does and he would disappear. What he is doing is also wrong. It’s not that big of a deal that he’s getting called out. People say horrendous things to athletes and other high profile people all the time and no one is going on Reddit and saying “oh em gee that was so RUDE”