Ok, here's the deal....
Remove the badge from the equation. Had this dude pulled to the spot you were standing in and demanded that you moved, and rather than showing you a badge of some sort, showed you his fist and said "GTFO" what would you have done?
Personally, I'd have moved. Not because I'm a wimp but because clearer heads prevail. There's no sense getting into a fight over a parking spot. Further more, I'd have been carrying -- and no matter what sort of fight you get into, if you're carrying, a fight automatically becomes a gun fight by proxy.
Most people in this world would have cussed you pretty good under their breath but never confronted you as you stood in that spot. You happened to catch the small percentage who will, and he did, and he happened to have a badge of some sort. The badge isn't the problem. The fact that he was confrontational with you is the problem, right?
Big deal. I'm not excusing his actions, and definitely think the guy was a douchenozzle of the highest order -- magnified by the fact that he gave the impression of being a cop -- but the fact remains that you got to go home, physically intact, and had a nice dinner with your date. You won. Not him.