Back to REALITY: the atheists followed the same process for getting a display space, and it is the atheists' displays, not the nativity scene, which were vandalized.
You also keep posting as if the tradition part changes anything. It doesn't. That space doesn't belong to the nativity folks, any more than a certain seat on the bus or the train belongs to you just because you happen to get it most of the time on your commute. The holiday space belongs to the public, not to any particular constituency within that public.
Never mind the fact that putting up signs doesn't prevent anyone from seeing the nativity scene. Apparently, those poor fragile Christians are just so incredibly sensitive and vulnerable that using two of the PUBLIC display spaces instead of their previous fourteen PUBLIC spaces sends their world spinning. Oh no! Whatever will they do! Wherever will they go!