If a county gives a mandatory evacuation order, then the hotel has no choice. Everyone must leave. Although there will always be a few stubborn homeowners who try to brave it out, emergency services make it clear that during the evacuation period you are completely on your own and once the bridges are closed, you can’t change your mind. My sister is on the ride out crew for a beach hotel in Brevard County. There have been times when an evacuation order was issued, such as in 2004 for Frances and Jeanne, and all guests had to leave the hotel because there would be no employees there working until the evacuation order was lifted. Other times, such as last fall with Milton, it was not expected to be as bad on the Atlantic side as it was, so no evacuation order was issued and my sister had to be there to assist any guests who decided to stay. Vero Beach would not have a choice about closing if a mandatory evacuation order was issued but if not then there would be more leeway in how they want to handle it.
Walt Disney World should not have to worry about any kind of mandatory evacuation order due to their location. The only resort they proactively evacuate is Fort Wilderness, due to flooding potential and the high number of large trees that could come down on a cabin or campsite, which is unlikely at any other resort on property.