This may provide some more information.
I, and I suspect many others, are not aware there was any legal mechanism for a government in the US to prevent you from selling your labor to someone else, assuming there is no contract forbidding it.
I don't have a clue if there is a provision addressing group recruitment in those regulations, but it wouldn't be shocking.
In general hospital regulation has lots of room for improvement...there's this idea that more hospitals will be more expensive and that it is good to move services to lower cost facilities. Neither of those make all that much sense. Competition and utilization are good things, not bad things.