I would do this today. An idiot on the road is one thing, but he walked into your work and confronted you telling you WHY he did what he did. That's enough reason to believe (convince the courts, should it ever get to that point) that what he did on the road wasn't unintentional, but a case of road-rage. Heck, the "I hope you crash one day" line combined with his actions could be justifiably problematic for the civic driver one day.
And, just for the sake of argument, what he did is considered 'performing a stunt' under HTA 172.
8. Driving a motor vehicle without due care and attention, without reasonable consideration
for other persons using the highway or in a manner that may endanger any person by,
i. driving a motor vehicle in a manner that indicates an intention to prevent another vehicle from passing,
There have been cases in which drivers have been charged after the fact. I wonder if the store clerk could be a witness to his statements?