You can be sure the BIG12 was/is EXTREMELY concerned about what happened with 1 second remaining on the clock.
I don't know what the communication was between the refs and the BIG12 officials during that long 15-minute break as they were reviewing the play and trying to clear the field, but it wouldn't surprise me at all if the refs were told to waive all penalties, diffuse the situation, and just get out of the stadium safely.
Imagine if BYU had taken over possession at the 30-yard line...
Our probability of winning would've risen from ~ 0.5% to maybe ~ 10%. Still highly improbable, but vastly better odds for BYU.
And imagine if BYU had somehow scored, while 20k ASU fans waited just yards away from the BYU players and the refs... not from the stands, but ON THE FIELD.
I'm not being dramatic or hyperbolic when I say that was a VERY dangerous situation.