I am trying to imagine this scenario, so your following a motorcycle, you have a clear view of the truck in front of it, and you go over the crest of a hill and see the truck's brakes lights come on (assuming here), then it swerves to the right. Would you not immediately hit the brakes as that is out of the ordinary? I know I would, then the motorcycle sees what is happening, and he swerves the other way, Not really sure why he would swerve the other way, but OK, at least he was paying attention, and still the trike rider has not hit the brakes, nor has he pulled to the right like he should have, despite everyone in his lane doing strange things, and he plows into the truck. Seems hard to believe it could get this far.
I think that trike rider needs to stop riding since he is obviously not paying attention.