Stupid.
I'd like to say, all of this over a handicap parking space? But I once had the police come over an 'argument' about a handicap parking space with an irate man. And I thought I might have to shoot him he was sufficiently aggressive.
<I debated, but I guess I'll tell the story, I may have written about it here before>
I was in college and it was a Saturday and I'd gone out fishing. On my way back home I stopped by the Starbucks my roommate worked at. I didn't normally go to that store, because it was pretty far from our apartment, but it was near the fishing spot. So I pulled up and parked my Mustang out front and went inside for a drink. Maybe 10 minutes have passed and I'm chatting with my roommate and sipping my iced tea, when a man comes into the store.
"Who's Mustang is that outside?"
I turn and look over at the man and I say, "Mine. Can I help you?"
"You parked in a handicap spot you son-of-a-bitch."
"Excuse me?" - I look out the window and sure as your born, I had accidentally parked in a handicap spot. It was an honest mistake, the way the parking lot slopped, I simply didn't see the painted marking on the ground.
"There is no excuse for you, you piece of shit!"
"Sir, calm down. It was an honest mistake, I'll move the car now."
"Damn right you will, you fucker! I drive my handicap father around and I don't even park in handicap spaces when I don't have him with me, because it's wrong!"
At this point the man is moving closer to me and my roommate has already moved to call the cops, due to the man's agitated nature.
"Sir, you need to calm down. As I said, I'll go move the car."
"Don't tell me to calm down. And move the car already!"
"I can't drive my car and have a conversation with you, in this store, simultaneously."
And then he started towards me at which point my roommate cut in, "The police are on their way here. SIR. You're going to need to leave now, or I'll have you trespassed."
At which point the man becomes irate and starts screaming at me and my roommate, but fortunately for him, he stays fixed to the floor and just keeps yelling. About 45 seconds go and the first cop shows up, lights and siren blaring. They come in and immediately cuff and stuff the guy and then start figuring it out. When the cop asks for my ID and I produce a CHL and DL he asks me if I have a gun, "Yes sir, I do."
"Good thing this idiot didn't try to fight you, huh?"
I shrugged. The guy ended up with a trespass warning and advice to not scream at random people in stores, the cop said, "This is Texas, sir. You never know who might be armed."
I moved my car (after the police cruiser unblocked me), the cops confirmed that you could not, in fact, see the painted handicap emblem from the angle I parked at, and store management put up a handicap sign affixed to the column in front of the parking space so it could be seen to prevent such accidents from occurring. Thankfully, no shooting occurred.
Point is. I've seen stupid people get mad over stupid shit before, like a handicap parking space. And to have a guy become supremely angry at me, over an honest mistake, to the point where I seriously thought he might try to assault me, I can see precisely how something like the story above transpired. Of course in the OP story the roles are reversed. Regardless it holds - It's not your duty to police the world, if you don't like something call the police and be a good witness.