a) I'm not the author so can't comment on what they really expect. But since they released the work under CC I'd suggest nothing, other than recognition, and based on the post after they finally realised their true reason for being hurt, I think it was also about being treated correctly and with respect.

b) INAL, but in the UK: "you automatically get copyright protection when you create: original literary, dramatic, musical and artistic work, including illustration and photography original non-literary written work... ". Assuming it's similar around the world there's nothing dubious about their claim, they didn't sign it away.

Regardless of your opinion of the person or their motives it seems they are within their rights to do what they've done.

> His claim to own the rights in the first place is totally dubious.

Whether you care for him as a human or not is entirely irrelevant to the rights to his work.

If there was no legal agreement, he retains the rights to it.

It’s not ambiguous.

> Did the author really expect that he would be getting royalties to all the Minecraft end text teatowels and fridge magnets as part of the deal?

No, and I feel like he made it extremely clear that this story is not really about money and his feelings are not driven by a lack of royalties.