As we've discussed in previous threads the "stay and play" requirement in 3-5-2-d is a live ball foul that's triggered by the snap.
d. Substitutes who become players must remain in the game for one play and replaced players must remain out of the game for one play, except during the interval between periods, after a score, or when a timeout is charged to a team or to the referee with the exception of a live-ball out of bounds or an incomplete forward pass (A.R. 3-5-2-VI) (live-ball foul) [S22].
I sense that a significant number of NCAA officials believe 3-2-5-d infractions should be enforced as a dead-ball foul. And presently, there is a bit of confussion regarding penalty enforcement for all infractions listed in 3-5-2.
Evidence: Play #9 in 2010 NCAA Bulletin #3
9. The ball is dead following a play that resulted in a first down at the B-40. Eleven
players of Team A, which runs a no-huddle offense, are going to their various spread-
offense positions in preparation for the next play. The ball is ready for play when
A22 runs onto the field from his team area, and after he passes the top of the
numbers, he or the coaching staff apparently realizes that he is the 12th player. He
then turns and runs back to his team area. The ball has not been snapped.
RULING:
Dead-ball foul for a substitution infraction. By interpretation A22 has
become a player by entering his team’s “effective huddle” and thus must remain in
the game for one play. Five-yard penalty. Team A will have first and 15 at the B-45.
(2-27-9-b, 3-5-2-d)
When questioned about his Ruling in this bulletin play versus the wording of 3-5-2-d in the rule book, Dr. Redding acknowledged the discrepancy, but indicated that he planned to review and possibly edit all the passages in 3-5-2.