Report to the authorities. Get a case number, to ensure a report is actually recorded, and then follow up on it.
Telling his boss isn't likely to have the employee held accountable, as it would only make the boss look bad too. I'm sure they'd be more than happy to bury any incident internally.
Drivers like this are eventually going to kill someone, and that needs to be pointed out to the authorities. The authorities need to start taking killing people on bicycles seriously.
If you get resistance or "eye rolls" from the authorities, I would ask them: if they were on a bicycle, and were screamed at, yelled at, threatened, by someone operating a motor vehicle... how would they deal with that? Is your life less important than theirs?