If the Nautilus is decked out with the mercenary keyword in all of her glory, gets sunk while she was carrying the Neptune’s Figurehead UT, does she get placed at her home island fully repaired like the UT States, or would she not because of the mercenary keyword.
Mercenary’s docking restriction prevents Neptune’s Figurehead from working, so the ship just sinks and doesn’t come back.
The only way to potentially save it would be to cancel the Mercenary keyword during the same turn, before it sinks. In that case it would return home like a normal ship, but then would immediately undock at the end of the turn when the cancellation wore off.