Well, this isn't really an MTB-issue, anyway, but let's be clear: the "No Bikes" restriction isn't aimed at mountainbikers, but at BMX/Street riders that have three problems in skate parks:
1) Their movements are somewhat incompatible with the flow of skaters,
2) They typically use metal grind pegs that trash concrete coping in pools, and
3) They are detested by skaters who are used to crying "victim" or "rebel" but are quick to be The Man to anyone not just like them.
Either way, I say Hurrah to the new skate park and I have no problem at all with the anti-bike restrictions in a SKATE PARK. Notably, skateboards aren't permitted on BMX tracks or MTB parks, either.