I agree, go for the throat. He's only bluffing. There is no way he could have observed traffic in either direction to be sure that the U turn was safe. Do you have to be able to see for 100 metres or so before you can U turn? AND he was doing it from the wrong side of the road, near an intersection.
He'd have a tough time trying to prove that he was driving with due care and attention. You may have been not doing the right thing in entirity, but that should be considered separately to his actions. I'm sure there are about four road rules he has broken here.
The reason you drive defensively is to avoid accidents with people who are doing unexpected things, like you were.