Agreed 100%. Nick can do whatever he wants with the money. He won it fair and square and doesn't owe anyone anything.
On his reaction at the finale, the main question I have is what was he supposed to say? How was he supposed to act? Quite frankly, these people talked down to him and dismissed him the entire season. They did it again at the finale, telling him he didn't deserve to win. Seriously, they needed to get off their high horses. Nothing he said was going to make it any better. Nothing he said was going to make it ok for her. She made that clear. He told her, point blank (and very clearly I might add) why he chose Keep. She still continued to ask him why he did that. If she wasn't going to listen to him the first two or three times he said it, then honestly, what could he have said that would have fixed things for her? What did he have to apologize for? He is entitled to change his mind, and I actually thought he made that clear at the finale. He had intended to share. And then he watched the episodes and saw how people were acting and what they were saying about him. He changed his mind. He is entitled to do that and doesn't owe her anything. She made the decisions in the things she said and what she and her clique did. Own them and deal with the consequences. I actually thought he was much more reserved than he could have been, given what they said and did all season.