As others have mentioned, park authorities can restrict you from flying from within the boundaries of a park. Those parks can be local or national, and everything in between.
So, if you were flying in the park, you were illegal. It was nice of them to just give you a warning.
However, if you weren't on park property, he overstepped his authority. Big time.
No local authority can prevent you from flying over any area. That is strictly the domain of the FAA. For some reason, California cities and counties seem to be the ones that like to make rules they can't enforce. It must be a California thing?
But just because they aren't supposed to control the airspace, doesn't mean they won't cite you. If they do, you may have to fight it.