I feel that they are unable to prop the door open because the local fire regulations don't permit it.

Here in the UK all doors to all rooms must be able to close themselves tight shut once opened and no further force is keeping it open. If a fire took hold in that room it would quickly spread to the corridor making your evacuation difficult if not impossible. Maybe they could relocate you to an area that wasn't being used as a display room?

Did you asked to be moved to a quieter room or some form of compensation. I believe you should have been advised of the event so you could have made a choice. Not only would you have been not troubled but your perception of that hotel would have been higher.

Tom,

I would have asked them to use a door stopper. Every hotel has them for Maintenance and Housekeeping. And if they would have said no, use the news paper and make a stopper out of it.

It's pretty sad that the hotel didn't respond to your request.