But, if you look at the video from behind, although Cooper's front wheel is turning left, his bike is still moving straight or to the right. He never comes in beyond mid track.
If you look at the first lap Kye Thomson rides a similar line, albeit that he doesn't scrub off speed by over locking. Maybe Cooper was just following the line Kye took on the previous lap, thinking that was the racing line
When people say 'what else could Luke have done' then look at the line Jody Scott took at the end of lap one to go inside Luke and much closer to the white line.
I doubt anyone is going to change their mind about what happened and who caused it. Of course, these incidents happen in the blink of an eye. Given injuries to riders elsewhere over the last few days I am just glad that the injuries here appear relatively minor (although any concussion is not to be treated lightly)