I like the spirit of the idea (keeping them away from others), but other than that, it's not a wise idea:
>Keeping all the passengers on board instead of letting them disembark on land is a strategy that can backfire, however, according to experts, because the ventilation systems and close quarters of cruise ships make them ideal places for illness to jump from one person to the next.
>“They’re not designed as quarantine facilities, to put it mildly,” said Don Milton, an epidemiologist with the University of Maryland.
>Milton, who studies the spread of virus particles in the air, said recirculating air on a cruise ship’s ventilation system, along with people living in close quarters and in communal settings, make the vessels vulnerable to the spread of infection.
https://www.usatoday.com/story/travel/cruises/2020/03/07/cor...