FWIW, I reached out to the organizer of a local competition about this.
"I think you are correct, there isn't really anywhere else for that kind of cider.* While I can't say that the judges will know what to expect while judging a '100% Brettanomyces fermented cider with dry hops', I would recommend giving them the best description you can to point them the right direction and make it obvious that this was intentional.* This is something that can be a challenge with 100% brett for anything, since there are too many different combinations and limited experience at the homebrew level, let alone at the judging level."
I hope this helps anyone who might also be looking for an answer to this particular question.