Where in this document does it mention stopping the clock for the player's helmet coming off? Is it handled like an injured player where we let the play continue and enforce the PF or sit-out-one-play condition when everything is handled? If so, it seems to me that if an OL or DL helmet comes off, you're ALWAYS going to get the PF for continuing to play without a helmet. I dont see how a guy in the middle of that would be able to just stop playing.
Edit
Nevermind, I see the clock part in the second sentence "The clock will stop at the end of the down." However, my second comment remains.