Who is "they?" Granted things change, but I dived for years in the Middle and Lower/Slower Keys and only ran into that issue with one particular dive op (no longer in business) that had more rules than a catholic girls school (sorry, not PC
). The rest of the ops if given a days notice would dig up another diver or one of their DMs would hop in if there was only one diver and they were already going out with snorkelers. Sorry you've bumped your head on the situation because I certainly enjoyed a lot of laid back dives on the little patch reefs in the area. Good luck.
According their website Captain Hooks still puts a guide in the water. I know they used to...unless they are the "they" you're referring to...
Enjoy Florida Keys Diving & Snorkeling with Captain Hook's