We had the same thing occur in Northern California. As soon as we pulled in a guy came up all excited and was telling us, through the window, that there was a guy three trucks down that won at the casino and was celebrating and handing out money. As a big guy and a retired cop, it's usually pretty effective when I tell them to walk away. This guy turned and went after some others.
I can think of only four instances in 40 years of RVing, the one above being one of those, where we were approached by a dirt bag. They all stepped back once they new I was serious about them leaving.
I would recommend that most just leave and not deal with anyone who appears to be a threat. Even though you may ignore them, it's hard to see if they're attempting to vandalize your RV or toad. I scan our surroundings thoroughly when we go into areas like rest stops. If they look bad, we just move on. As a cop for 35 years, I have handled this type of stuff my entire career and I'm fairly comfortable in most situations.
Most police officers will tell you that they are taught that when they're off duty and especially with their family, never get involved unless absolutely necessary. Your only involvement should be to make a phone call to local law enforcement and be a good witness. This is what everyone here should do when confronted with these types of situations.