Let the play go off with 12?
 

Last Friday in Mass (NCAA rules); I'm underneath with the BJ on a try. We count 12 on Team B. Count 12 again and kill it presnap for illegal substitution.

After the game, I was wondering if this might be one time to let the play go off?

I understand (and agree with) killing it normally, so as to avoid "unnecessary" 15 yard penalties. But on a try from the 3, we can't go 15. And it can't carry over to the kickoff.

If A kicks or fails on a 2pt try, they'll still have their option to try again from the 1.5. But if they convert, chances are they decline. And we avoid a stoppage.

(Of course, if B blocks the kick or intercepts the try b/c they have 12 and runs it back 95 yards, the plan kinda backfires.:))

Yes, kill it pre-snap. No good can come from letting the play go and penalizing later.

This probably wasn't the case, but what if B had 12 because they were late adjusting to an unexpected "show" of 2 pt. try by A? Kill the play, dead ball foul, and you're letting B adjust their players while A loses surprise.