Even though this incident was not the fault of the religion itself, it would be just as insensitive as the Mormons building a church where the Mountain Meadows Massacre happened, the Japanese building a Shinto shrine in Pearl Harbor and the Germans building a beer hall in the ruins of Auschwitz.
All of Pearl Harbor belongs to the military, so that won't happen. But if it were in private hands, then it could be done.
Auschwitz belongs to the Polish government, so that also will not happen.
The Mormons want the Mountain Meadows Massacre to go away. Before Xerox machines existed, they would pay thousands for books published on this so they could destroy them.
I really do not see how they can prevent this legally. And it isnlt at "Ground Zero", it is just nearby. I am sure it will be totally possible for anyone to ignore it.