Perhaps he should see if he can work remotely from the ship. That way he would stay occupied and as an additional bonus, won't have to burn as many vacation days. 😊
As an aside, I took a Journeys Cruise out of Galveston last winter, and the thing I noticed was that it had an exceptionally large number of elderly people - way more than other Journeys cruises I have taken. Not that there is anything wrong with that. As long as you don't mind dealing with a huge number of scooters (we actually encountered scooter traffic gridlock on a few occasions) or the huge demand for early YTD seating times, you should be fine.