I agree that it would be something that shouldnt be happening and it would be frustrating to have to use an air mattress or switch resorts..However, accidents happen and while yes, this is a big deal, there really is only so much they could do last mInute to ensure safety.
Now, if there was no offer at all to move them to another resort the next day, or compensation offered for continued agreement to use an air mattress, then yes, I would be upset and actually complain.