From the information given I can understand both sides of what happened. Mistakes are made. The group may have reserved the same spot and paid for it.
I personally would not have suggested that someone move their gear and set up again for one night only to go back to original Site the next day.
I have a disability parking permit that entitles me to 1/2 price. The sites are made for convenience. Because I am not in a wheelchair, I always tell the staff, if someone comes in needing that Site because of a chair or other needs, we will gladly move for them. We have done this before. I still get my discount. Isn't it nice to make someone else's holiday enjoyable also. Sometimes we really have to choose our battles and while doing so, look at everyone's point of view.