It kind of depends on the duration and application.
For the lubes we put corrosion inhibiting additives in everything that took oil, from main generators to the smallest pump gearboxes and tried to run the equipment long enough to mix it around. Larger capital equipment like generators you’d want to periodically pump the oil around and roll the equipment over. The manufacturers said it the systems could be reinstated without flushing, but I would have wanted to flush/replace anyway. That was back when we were looking at 1-2yrs stack time.
For fuels, there are also additives, but ideally you run the tanks down that won’t be used. These obviously aren’t two-stroke outboards, but if you’ve ever left gas in your boat over the winter without winterizing the engine you know how fun it is come summer.
But reading that article it sounds like they intend to keep some generators going. And they’ll likely need to. I’ve seen external power/generators used to run dehumidification equipment. But a vessel of the scale and internal volume (read: 6000 mattresses) will require a significant amount of power to run that kind of equipment. Even if a ship is lucky enough to get pier space, I don’t know enough about cruise ship shore power to assume you have enough juice for that. So if your’re running ships generators, good fuel tank planning would negate most serious concern about tank issues. For empty tanks there are vapor emitting corrosion inhibitors on the market.
Other issues are related to electronics. Not just thousands of cabin TVs, touch screens, bridge nav equip, but everything related to engineering system function that has a PLC or a memory. All that needs to be backed up and stored. In humid environments, circuit boards don’t like rust either.
How many lifeboats on a modern cruise ship? Best grease the crap out of those fall wires and hooks. I’m sure a COI on return to service would just be a nightmare.