Like all encounters where you are threatened with bodily harm(or even death),
you have the right to stop the thread(if you can't disengage), but once the threat is 'over', you don't have a right to continue..whether use of a fist(weapon) or other 'weapon'.
Yup, he might have been arrested and rely on witness' but the driver had the 'weapon' next to him also. I think I would have called the cops..AFTER 'stopping the threat'...
BTW-I had a shouting match in Longmont with a guy inna truck who thought I didn't belong on the (far right side) of the road..shouting match while in truck, he stopped ahead and grabbed a tire iron out of the back of his truck and started walking toward me...Wasn't sure of THIS outcome but scary...
He huffed and puffed, I said nothing, stood behind my bike..he got back in and drove away..
PM me if you'd like to know how I would respond to a similar scenario these days..
..BUT the idea is to stop the threat or otherwise disengage if you can..