OK, just looked at the UCF situation on YouTube. The kicker recovered the blocked kicked, and was attempting to advance, when he got engaged by a BYU defender, who tried to wrap his arms around the, now, ball carrier at the shoulder level. The BC twisted and dipped in trying to get out of the defender’s grasp, resulting in the defender’s arms sliding up onto the BC’s helmet. Without grasping the helmet in any way - only the friction of the defenders arms on the BC’s helmet - the BC helmet just slipped right off as he was going to the ground.
A flag was thrown by the H, more on the ‘liklihood’ of a foul than actually seeing either a true facemask foul (grasping the mask or a helmet opening), or even continuous helmet contact. Don’t know if the RO got involved in that, but the H picked up her flag. But, the legal scrimmage kick down causes the game clock to stop. So, the helmet off should not have generated a 10SS.