But if he's at M50 as musician GoH, then why shouldn't we list him like that instead of as "with"?

Along these lines, if he wants to be listed as Fan GoH or author GoH or fan/author/musician GoH, I'd be fine with any of those. We flapped back and forth during M49 as to whether Janny was an artist GoH or an artist/author GoH because we were trying to list her as she wanted to be listed (and were having some trouble figuring that out).