I trust the channel selection is a recommendation... if they're not monitoring 16 as well, that would be a violation of US laws or USCG rules...
More than a recommendation, 88a is THE working channel for Atlantis communications. Meaning that they are constantly monitoring both 16 (required by law) & 88a (which all the Atlantis vessels are tuned to for vessel to vessel communications/coordination).
With regard to the legitimacy of Atlantis' lease... Knowing the individuals involved in the process, the whole sinking of an 'underwater attraction' was a big deal, which took years... finally resulting in the State requiring Atlantis to lease the space in order to sink the wreck. Taken from 2005
Maui News Article: "Like the other Atlantis reefs, the state is being asked to grant a nonexclusive lease of submerged lands. The company uses the reefs that grow up on the dead ship as an attraction for its tours. But other people can also visit."
My understanding of the protocol mentioned previously, is with the intention of safe diving practices around the submarine. Atlantis purchased the Carthaginian, as well as the lease of that submerged land, specifically for their submarine tours. And while other people are welcome to visit, there are certain SAFETY PROTOCOL that should be followed to avoid possible hazardous situations while diving around the sub. Seems reasonable that Atlantis would ask for a heads-up on when you're going to be there, that you not approach the sub because the pilot has a limited field of view, and that visitors use the bow mooring they provide and maintain for visitor use, rather than the one they reserve for themselves.
Unrelated to the Carthaginian 'ownership', I also understand that a specific area of ocean there has been outlined for submarine operations... I don't know all the specifics, but I do know that anchoring is not permitted in this area... again, kinda common sense.
It seems irresponsible to let this go unmentioned, so let me say that while I can appreciate questioning the legitimacy of the u/w lease and Atlantis' rights to dictate protocol, I'm honestly confused by what appears to be an implication that Atlantis might be violating federal laws regarding VHF radio use... IMO to imply such is downright reckless and I cannot see how doing so adds anything to this discussion but flammable material.