I must agree, at least philosophically. I do not know about the "he owes the patrons" argument, because that was never any contractual agreement - no one forces anyone to contribute via Patreon. You, or anyone else, contributes fundamentally as payment for work he has already done (and to help enable/encourage him to do further work), but at no point are you paying him to work today or tomorrow. He owes you, as a patron of his art, nothing. If he gave you something you deem to be significant to your enjoyment of life, then you owe him - not the other way around. However, I do agree that he "owes" his art. Though I do completely agree that if the creator decided abandon work on the project, he should tell his patrons that. It is poor behavior to continue to profit from such a format as Patreon if one knows they have no intention of ever putting effort into that product again (though we have no idea if that is the case in this instance).I don't recall saying anything against his integrity. But you're wrong when you say that he doesn't owe anyone anything. There is an implied contract between patrons and the artists they patronize. He does owe it to his patrons to let them know if he has abandoned this project.
So, having clarified, I'll reiterate my previous statement. If he just ditched this game, then shame on him.
Real life problems happen, certainly, as do joyous events. And, yes, people can get burned out. It does happen. But if no serious disaster has befallen him, then he owes it to the people who have supported him to either finish the game or give us notice of its abandonment. And, if it were possible to owe anything to a story which you've created (I maintain that it's not possible.), then I would say that he owes it to this excellent game to finish it.
GRR Martin does not owe fans of his novels a conclusion. They bought the books he wrote and nothing further is promised. But i would argue that he owes the characters he created a conclusion to that narrative. In that context, your assertion is correct.