Correct me if I'm wrong, but I believe this is not cabotage. If they are flying from one US city to the Caribbean or Mexico that is no different than what all foreign carriers do everyday. Now if they are picking people up in CVG and dropping them off in MSY and then continuing on to Mexico, that is cabotage. But stopping and only picking up people is also ok. Qantas used to do JFK-LAX-SYD (maybe they still do, I don't know). That was not cabotage. And I don't believe this is either.