I would suggest that if there had been a private covenant on the properties surrounding the 9/11 crash, the owners would have agreed by 2/3 vote (or near unanimous) to amend the covenant to exclude building a provocative meeting place of sympathizers with the perpertrators of this calamity.
Or, if this was zoned in the normal manner, the zoning board should have changed the zoning appropriately.
Sometimes things are subject to change, sometimes extraordinary things happen as a precursor to "change". This was one of them, IMO.
Perhaps but...that point is academic. Because such contracts were never formulated PRIMARILY BECAUSE OF THE ZONING RULES YOU WANT TO BROADEN, We are left with a real live issue of whether to extend of limit the arbitrary power of politicians (at the federal level?) over a specific piece of land.