He'll finish writing it when hbo stops driving dump trucks full of money up to his house.
He hasnt written anything in 12 years. His wiki runners wrote awoiaf and 99% of fire and blood for him (he had written a short story, a small portion of rhaenyras story, released in the dangerous women anthology of short stories). he just rubber stamps his name on whatever as long as the checks clear, just like this show. How the fuck you think a "showrunner" is pleasantly surprised by the changes made to characters on a show he allegedly collaborated on?