However, you also have to take campbest's comment about possession into account because Buddy reaching back and touching it alone doesn't cause the violation, e.g. what if an ISU player had tipped it back there and Buddy was going after it from the frontcourt or what if an ISU player was the last to possess it on that side of midcourt. The ball had to have been possessed in the backcourt by OU and at that point in time have backcourt status.
Related to that, I thought the 3rd Q&A on
this page seemed to explain it, assuming the ref thought Cousin's possessed it. While Buddy didn't jump into the backcourt, he clearly had frontcourt status when he first touched the ball.
So, my view is that it had to have been the combination of Cousins possessing it first and then Buddy gaining control while in the frontcourt...neither of which I think happened.