CJ,
I think that you've taken exactly the right course of action. There is little that the police would have been able to do to them which would have had a deterrent effect, but you scared them and that will have an impact. Each will have noticed how the other was reduced to the silly little coward he actually is and so instinctively they will be more reluctant to kick the same procedure off again. As it happens you also kept the moral high ground by not thumping them.
I had something slightly similar, altough not as bad, once happen to me when a car turned right across my path when I had right of way, causing me to skid and nearly come off. The driver laughed and drove off. I guessed he was on his way to the local supermarket and so leisurely went off after him. Sure enough there was his car. So I waited for him and his wife to get back in the car, went up to the vehicle, tapped on the window and said, "Let me introduce myself: I'm the bloke you could have killed back there" and proceeded very forcefully but very calmly to lecture him on his driving. All the while he was trembling, really scared. His wife just kept giving him a "told you so" sort of look. I suspect that this was an effective course of action as yours.
Well done!