Was there an emergency at this hotel? What caused the elevators to be taken out of commission and under manual control for 15 minutes?

I'd be more concerned that there was no way to simply walk downstairs and out of the hotel. Or, if you are mobility-impaired, that the hotel couldn't do an assisted evacuation faster than 15 minutes - if there was really an emergency.

On the Hilton side, they may see a guest who's been offered BMG's (those can be valuable), then 20,000 points, all for a 15-minute inconvenience. It seems like they've made a pretty good offer already and at some point may just think you're complaining to complain.