As noted in the above story, and what I alluded to Quarantined Cruise Ship Is a Petri Dish of Coronavirus.
The quarantine was not working--as they had expected. More people continued to get sick--on the ship. The best option for USA passengers is to take the ride home and go into another quarantine back in the United States. As the article above states, all passengers will disembark next week and in order to fly back home, USA bound passengers will need to go into quarantine when they arrive via another mode.
I wonder how travel insurance would impact any of the above? Likely it is an exception mentioned in the fine print of the contract you sign.