They don't care. Back in February, my flight was cancelled because of a severe ice storm that shut down the entire northeast region of the country. There were no flights available on Friday or Saturday and the cruise left on Saturday morning. We checked Boston, Manchester, Providence, Hartford, New York, Newark, Baltimore... We even considered driving half way and catching a flight somewhere, or taking a train and then a flight. But nothing would work to get us there on time. Disney didn't care, though.
We were a bit lucky. Disney had recently changed our itinerary from an Eastern Caribbean to a Western Caribbean because the various Virgin Islands were still being strict about Covid-19 protocols and foreign visitors. So, we were able to cancel the cruise and book back-to-back Dream cruises out of PC instead for about the same price and without paying fees. But if that hadn't happened, we'd be out of luck without travel insurance.