Never served on a ship—but I have managed fire suppression systems in hospitals.
Every time we took the system off line we would have a security person standing with an extinguisher on every floor.
Yes, it looked silly. Yes, it consumed a ton of man-hours. But, we were not afraid of the building burning down—that wasn’t really possible. We WERE concerned with smoke control in patient areas. And...lots of O2 used on the floors.
I guess they did not want or think they needed to extend a fire watch.
I believe that fire codes require large public venues with automatic fire control systems to have a firefighter sitting at the control panel if they switch off the automatic response, which they do for things like games or concerts with pyrotechnics.
Of course, as the San Antonio Spurs found out, you have remember to switch off the automatic response...