You need 2000 hours 500 multi and your ATPL subjects.
At a guess, I'd say that Rex have raised their entry requirements for FO's so that they can be upgraded to Captain in minimal time.
Rex have plenty of FO's from their cadet scheme, but from what my friends at Rex tell me, they have almost no upgradeable FO's. If they can't employ DEC's, then FO's who can be upgraded in 6 months or so are the next best thing.
DIVOSH!
J3, don't get me started on the hats...