Had a vaguely similar incident. My wife and I often pass through a state park and pull off into the parking lot and walk over to a fountain refill our water bottles. There are a number of signs that say no bicycles , which of course we interpreted as meaning none in the park, not none in the parking lot. (a reasonable restriction for this park, IMO). A ranger pulled over and told us we had to leave. Having filled our bottles, we complied. I contacted the state parks department via email and they responded saying the ranger was wack and that they'd straighten him out. I don't know if they did, but we haven't been hassled since.