It doesn't matter. Fanart is fanart, you can't sell something that isn't legally yours.
The fact that he did as much as he did in the first place means he actually wanted to do the project, even if he wasn't paid. My assumption is he stopped because he reached a point where he didn't care enough about the projects to do them for free.
That's why he moved on, and it's probably for the best that he's developing original stories and characters now, I just wish he finished what he started at some point instead of abandoning it completely.


