Is it possible that the BA lounge in Miami is not operated by BA and is just some "shared" lounge?

Edit: No. Apparently, the word from the BA rep was that OneWorld emerald and saphires, and not just BA Silver and Golds, should get access at the Miami lounge too if flying on a oneworld flight. Who knows if the rep is right or not. BA reps for Gold Members are the same as for other people (the best I can tell) and are leagues behind the EXP desk.