Tourists have homes and jobs to return to, unlike the locals who require food and water. Getting the tourists out makes perfect sense, because it saves resources.
Anyone and everyone who is evacuated will initially require resources such as food / water etc... or do you think they will be driven to thier homes?? Once out - they will need to time to obtain tickets / transportation etc...
So, the argument holds no water. FEMA has set up evacuaton routes and centers for the processing of the refugees - screwing with these is just not a great idea. I would even be willing to wager that plans are being made / are in place to assist tourists in returning to the homes / home countries. None of this can be done effectively if everyone goes it alone.