It could be a hoax, but I find it difficult to believe, with all the other law enforcement involved, state and federal and overseas, and all the agencies involved, that they would all go along on this if all Boulder had was some emails.
But I admit, he looks more and more like someone just yearning for attention and involvement in this case in any way he can get it.
This guy's in a Thai jail for other reasons. This may just be an attempt to get himself transferred back to the USA, after which he can just say "never mind, I just needed out of the Thai jail!".