Way too much time left in the game to say this play was the difference in the game.

No guarantee he was scoring if Morrell didn't do that.
Hawaii kicked a FG to reach 13 points. A TD gives them 17 points.
BYU went down and scored a TD to get 18 points.

If you want to say that play won the game, then you have to allow for every other play to have gone exactly as it did, so as shown above mathematically, BYU didn't need to hold Hawaii to a FG to win the game.