That's conjecture, not proof. When was the semi's speedometer last calibrated? That's inconsequential to the argument though, so I'm not even going to argue with you about that. We can assume he was doing at least 68 if you would like.
You want us to believe that the collision occurred solely because of his speed. Where is your proof?
Just curious... why did you cherry pick the ONE question that is easy enough to explain away (even if it isn't proof) and completely ignore the more important question that is central to your entire theory behind posting the picture?