what would you do?

You did the right thing. I have called countless time during my commute to work and back(70 MILES ROUND TRIP) for people drinking a beer or some form of alcohol. If you have ever been on route 80 in NJ during rush hour its a nightmare, but add alcohol to the mix that is just wrong. I wouldn't beat yourself up. The man decided his fate. Lets just hope he doesn't take anyone with him.

Thanks
James