Many of the Caribbean based cruise ships have rescued a number of Cubans over the years, however, this for me is the first time I hear they are to turn them over to Mexican Authorities, doesn't mean it hasn't been done, it is just for me personally, it is the first time I have heard of this. I have been on three ships where we picked up Cuban Refugees and in saying that, we were headed for Florida as our next stop; for the "Oasis of the Seas", their next port of call was Cozumel, this is the logic disembarkation point for the disappointed Cubans.
The U.S. follows a protocol when refugees are attempting to enter the U.S., if they get to the beach and able to step foot on the soil, they are detained, investigated and if there is family who are in the U.S., they are contacted; however, if the refugee is caught while still in water, they are then sent back to the country of their departure.
The requirement of ships to go to assist a vessel in distress was treasured both in tradition and in international treaties, one of those treaties is the International Convention for the Safety of Life at Sea, created 1974. There has been no distinction between "yachties" on solo trips around the world and boats carrying asylum seekers. The Cubans, in general, do know when the ships are due to sail past. Whether it is good or bad weather, they will do their best to get out there and be seen.