what? why?
Are you speaking to me or Bobby?
You. I'm genuinely not sure what the issue is. I mean my son made a picture of a scene from nightvale radio and didn't ask permission to do so. Although I doubt they would care. So if the quality of the work is the difference between the two, I'm guessing your objection it's a compliment to the quality of Bobby's work. Aside from that I just fail to see the problem.
Bobby's graphic seemed like it was the cover for the book.
In fact, it is not. Bobby is seemingly making an unsolicited and unauthorized advertisement. It's not about the quality. It's about the representation. I don't know what nightvale radio is, but since it is well known what Chasing Eris is here, any post that seems to represent it will have an air of representing it. Especially if it looks like a book cover.
Oh. But fan art is okay as long as it doesn't look like an unsolicited and unauthorized advertisement? You know, I know nothing about legal stuff like this so I'm not really qualified to argue this. Off the cuff, I don't think it matters a whole hell of a lot.
(And, as a side note, you should totally check out nightvale radio podcast.)