What Treetop said. Plus there are a lot fewer medical facilities available on a ship and you can’t just get more help readily.
Also, on land society can continue to function when people are sick. There is always someone else available to do the job. Not so on a ship with limited numbers.
It's not just the TR and deploying units, though. The restrictions implemented in March remain in effect today because the DoD is still HPCON C-. Some highlights:
-There is still a stop movement of all PCS in effect - not just to/from the NY/NJ/CT area.
-Sailors who live on base are not allowed to leave base. Sailors who live off base have been ordered to go nowhere except work, home, and shopping for essentials.
-Many Sailors who live aboard ships are not allowed to leave the ship.
-Everything outside the NEX and Commissary is closed because they aren't mission essential.
-Leave outside the local area requires FO approval (again, not just NY/NJ/CT).
This is aside from at work distancing measures like mandatory masks, reduced manning, mandatory 14 day quarantine for coming in contact with a PUI or prior to underway, etc.
So the question of why we're still doing all of these measures until at least July 1 with a low risk population and no phase out plan communicated is a fair question.
On a lighter note...