Carlton, I can see no downside at all to your actions.

1) The claim that he might have had a legitimate reason to tailgate because he was in an emergency:

First, only an idiot would race down the road in an emergency without turning on his emergency flashers.

Second, It takes LONGER to pass from a tailgating position than from following at the proper distance; when tailgating, you cannot accelerate until you are fully in the other lane. If following at a proper distance, you can start accelerating before moving out into the other lane, and therefore spend less time there.

2) The guy just doesn't know how to drive properly, and did not understand the hazard he was placing himself in.

You have now explained it to him in a manner he is not too likely to forget.

3) The claim that you should have taken some action to ensure the safety of someone that was driving dangerously.

You did. You stopped him an a manner that did not hurt him, and removed him from the road before he hurt himself and possibly lots of other people as well.

4) The claim that you have caused all of our insurance rates to go up.

For a tailgater, high-centering out on a log is just about the least damaging accident he could have had. If the log had been a 24" instead of 8", and the other lane had traffic - what shape would he be in after the little BMW slid under the rear of your hard braking X?

Shoot, Carlton - you are a HERO! You probably saved this jerk's life.

How often can anyone perform such a heroic act, and have so much fun doing it??

Terry