This is the stuff I hate so much. The monument stood there for over thirty years and no one cared. NOW, due to the ACLU-backed anti-God campaign, EVERY ONE is a target. GRRRRRR.
They may be able to keep it on historical grounds, and if it's stood there uncontested for thirty years, WHY NOW? is a valid legal argument.
It's as if they're vampires who just got out of their coffins, roamed the land looking to destroy all that's good, and pounced on the tablet.