Dude was wrong, no doubt about that, but he still could have made life a little miserable for it. Perceived threat? People honk their horns all the time expressing their displeasure over something. Not sure how that constitutes a perceived threat. Loudspeaker? I'd have checked the car out real carefully at that point, not many people have loudspeakers installed in their cars...except for cop cars.
Situation was bad. Sometimes you only make it worse by escelating it. I had an 18-wheeler come up behind me a couple of weeks ago, and hit the horn well out (like 150 yards or more) behind me. 4 lane road, so first thought is "he can go around" but check of the mirror shows that he's in the front of a big bunch of traffic that's covering both lanes. I had the right to the lane, but it was also safe for me to move over and let the bunch of traffic go by, leaving me with clear road once they were gone. I could have held the lane, but it was reasonable for me to move over and let them go, making both my life and theirs easier.
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Tom
"It hurts so good..."