Please see post 4,6, and 8.
I do think it’s a bit fishy, but would really like to see a detailed explanation by investigators. It’s theoretically possible that it happened the way he says it did — just seems like it’s in the probability range of a first time golfer hitting a hole in one on his first tee-off. What COULD have happened is that when the truck first moved forward, it hit the side of the wheelchair, and since neither the side of the wheelchair nor the grill of the truck are perfectly straight, it could have simultaneously lifted one wheel off the ground while causing the chair to spin around 90 degrees on the other wheel. With those rear handles sticking out backwards the way they do, possibly some panic reactions from young Mr. Carpenter like pressing a foot to the ground or grabbing at the grill, could have provided further assistance to getting the improbably job done.
I sort of doubt it was a suicide attempt. But given how unusually calm the victim seems to have been, I wonder if he isn’t somewhat mentally impaired, and maybe stopped in front of the truck to admire the big shiny grill. If the truck driver had seen him approaching in a motorized wheelchair doing a decent clip in a straight line, and then looked away while waiting for the light to change, he might have reasonably assumed that the wheelchair had continued on its path and gotten well out of the way, even without actually seeing it emerge to the other side of the truck.
All very weird. Glad everyone’s okay. Suspect engineers at the company that designed the wheelchair are presently engaged in a very unusual special project.