Absolutely no excuse for this. He should be charged with assault with a deadly weapon at the least. I spend a lot of time in my car and understand how he could become frustrated if stuck behind a bicycle in traffic, but that's no excuse. You just have to bide your time, eventually you'll get the opportunity to get around the cyclist safely. Has he tried to run slow moving grannies off the road in the past also? Maybe he thought the cyclist was flipping him off when the guy "raised his hand to call attention to himself", but again that's no excuse.