This is from the Daily Herald article on Hill's injury,

"Taysom got hurt on the third to the last play in our game against Utah State," said Cougar head football coach Bronco Mendenhall. "He received a pretty clear signal from the sidelines that meant the clock is going and he interpreted that to mean run the play. He took his eyes away and 'victory' was signaled in, and right after that he got hurt.

Doman explained that when the sideline realized Hill was going to run a play, they tried to get a timeout but the snap came too quickly.

So, to your point, looks like they tried to call a TO. I don't know that is the right call, I think you let the clock run, but then again, I'm a guy typing on a keyboard...