Besides running him off the road, what else could I have done to the man who ...

My guess is that you had some pervert psycho hiding in your back seat, who was just waiting for you to be alone. That hero in the car in front of you slowed down to try and save you, until his exit came up and he felt like going home. Go check your backseat. The guy probably fell asleep back there due to the sheer boredom of waiting.