Keith your were right in your first post. The only reason rider did not get a chance for a wave is due to his speed approaching the truck. He tried to just fly by him. Had he slowed down and waited for a better time to pass than a turn maybe the truck driver would not have reacted like that. Slow down pull in behind him and then pass sanely not kneedraggin at 80.
I don't think we'll ever know if you are right or not Saiid. There was no pause on the truck's move to ditch the rider. That was pure emotion no rational thought about it at all. If the rider had been going slower and tried to pass, the truck may have well been successful in running him off the road....