Tonsils in, everyone!
There are two common reasons why threads disappear:
1) The thread contains some information (i.e. something that could cause legal problems) that needs review by the admin folks, so it gets moved (at least temporarily) to a private forum where the review can take place,
OR
2) The person who started the thread decides to delete their initial post, which therefore deletes the entire thread.
Everyone is quick to jump to conclusion 1 (and then of course scream "censorship"), but I've just had a good look in the private Admin forum and can't find it anywhere. If it had been marked for review, it should be in there. There's not even any discussion regarding that thread.
So, while I'm not 100% sure that it hasn't been moved by an admin or mod, it doesn't appear to have been moved in the normal way.
Does anyone know who is the author of the original thread? Has anyone tried to contact that person?
Perhaps it's wise to explore the possibility of option 2 and settle down with the accusations in the meantime.