Who is “they”? Japan?
Quarantine 4000 people at the drop of a hat?
The ship is the best place for now. There is not enough knowledge to handle 4000 people safely ashore.
For starters, since we’ve been willing to evacuate Americans from Wuhan and hold them in quarantine here, we ought to have done the same for those Americans on board. Other countries should have stepped up for their citizens as well.
Anyone getting on a cruise since the threat was known should be on their own, but this was earlier on. But that ship is a certain petrie dish for spreading the virus at this point.