We have always said here, once you leave the ship without contact info, it's basically over..but, John has the ability to pass along a well done, sort of message to the crewmember. If the OP is looking to persue anything, more, another cruise needs to be booked
He recently tried to help someone, but the name was quite common, but, you are correct, security issues make it difficult, unlike when I first cruised, on RCI,you were given a booklet with passengers names, and, hometowns!