It is not normal procedure to put in peoples flight itinerary if they are doing their own air travel. It is the passengers responsibility to turn up on time to the ship.

I would also feel it is the ships responsibility not to sail prior to the scheduled departure time if all booked passengers have not boarded.

These people could have come in days earlier and been touring the island and not planning on boarding until a few hours before departure.

I have no idea what happened here. It occurs to me that the Regent spokesperson may have been misquoted. Would not be the first time.