It's long past time for our Police to step up and start citing incidents that CAUSE road rage. This is probably an incident that was caused from the driver feeling no one does anything to help reduced idiot driving. I'm not justifying the person one bit but if you are at all observant, you can see people do rude things while driving all day. In my day we put social pressure on people to behave. Today it's called "road rage" to do this(not what that guy did...that is battery and disgusting.
1) People not moving out of the passing lane.
2) People cutting their left-hand turns into the other lane of traffic.
3) Entering a highway and crossing the solid line to cross 2-3 lanes of traffic.

It's time the Police gets back to addressing these things and be VOCAL about doing it. Then some may not feel the need to take corrective action into their own hands. Again, this guy was wrong, waaaay wrong. But it's a sign of taking out one's frustration with dealing with idiots all day long.