How would you feel about someone building a grave over you grandmother and father?
If your dead grandparents to to upset they can turn it into a country buffet or shuffleboard area.
Make all the jokes you want but it is not funny in the least. we get no respect when we are dead it is not like we should expect any when we are alive.
Would I be worried about the Native peoples of the area feeling offended that a site sacred to their culture was just bulldozed over to make way for a building? Yes.
Was the rumor proven true? Were any bones ever found?
A lot of times people like to spread rumors when there is no truth to it all. For example, my friend was a superintendent for a local building project, and after it was finished I heard some people (who were not at all involved in the construction) spread rumors that Indian bones were found during construction and the government almost shut it down, etc. I asked my friend about it (who supervised it all from excavation to the finished project) and he said that no such thing had ever occurred.