Sorry to hear about your excitement, John, but you're just too used to reasonable drivers.
Over here in the land of the distracted soccer mom, the texting teens, and so on, I'd *never* hang out next to a car if I could avoid it. In your situation, I'd have slowed down to let the cop and the driver in front get ahead of me, so I could watch what was going on from a safe distance. Absent the cop, I'd have passed the driver as quickly as was reasonable to get to some more open road.
Hanging out next to a car here is a recipe for an accident.