One thing about motorcycling is that you tend to end up where you look, and a lot of people crash into oncoming traffic in corners because the focus on the oncoming car and not on getting around the corner.

I get the feeling that this guy tried to veer, and then refocued with all his attention on the truck that was getting closer and closer, and that made it quite impossible for him to evade. He could have saved it by doing a million things, but large and threatening objects that are approaching usually demand our attention. Silly, primeval behavior.