Yes You are correct BYU did screw up the end of half in several ways… But at the end of the half the officials messed up as the illegal snap happened with the :12 seconds on the clock. By rule, the 10 second runoff would leave 2 seconds and the clock would start on the official’s signal “ready” and BYU would have time to get a single snap off if they are quick, but by Rule you must have a minimum of three seconds to snap and spike the ball and get another play off so they can’t spike the ball and get another play. You have to have 3 seconds or more with a running clock to get the spike off and be allowed a second play kind of like you have 3/10ths of a second in basketball to catch and shoot otherwise it has to be a tip by Rule.