Hi Intro--
I think that this guy was being very aggressive. I do not think that you safely, calmly following him was wrong at all. Maybe you did do him a favor, if in fact, you managed to make him think about his actions.
Long ago (and far away) I was out on "the strip" with a car I had that looked like nothing but secretly had an engine like a rocket (it was a prototype I was fortunate enough to acquire). I used to win plenty of money racing this car and often times the loser of the race (always a guy) would get ticked for losing to a girl in a seemingly nothing car. One of these sore losers got really aggressive afterwards, tailgating me and in general harrassing me pretty badly. I got off the strip for a while to get away from him and his buddies. A couple hours later I returned and saw their car wrapped around a pole and people being carted off in ambulances. If you made this guy think even for a moment about his actions, you never know, but you may have contributed to preventing such a thing happening to him. Not likely but hope springs eternal.
Regards,
Julie