Don't know what kind of Hilton it was, and whether it was a franchise or not, but normally you would evacuate even on a false alarm. It's true they can't look after every stupid guest, but fire safety rules are not that lax where I used to work.
If the points letter you got was really from the GM and not FO, try going back to him and explaining the situation. If that doesn't work, go after Hilton customer reps