Bottom line is that it does not work. No credit if you don't fly. If the BP is scanned, the pax goes into the head count. When the count is off, the aircraft will be held at the gate until AA can figure out who is missing, offload that person from the manifest and move on.
At a minimum, the other 150+/- people on the flight have been delayed 30-45 minutes and you get no credit. At worse, you get the boot out of the program.