I watched it at home. The camera angle was not good enough to over rule. I thought the toe was right over the line but the cleat height allowed a gap. A shot down the line would have showed it. Also though he did not have control of the ball as he came down.
How did the defender allow the receiver to get behind him? Just wrap him up and take the PI call. That would get them half the distance and one more play.
Still it did not come down to that one play. The failed 4th down could have been a FG. TWII fumbling in the redzone. 4 punts in the second half on possessions of 3 to 5 plays. 3 Oregon scoring drives in the 4th quarter of 96, 75 and 75 yards. Really bad play on both sides of the ball and throw in some bad play calling.