Notably, checklists (checklist cards used in place of Double Faced Cards) are not deck lists.
Daniel, I understand your concern that players A and B are not punished equally. The fact is that B, in this situation, did not commit the IPG infraction Marked Cards. It is impossible to have Marked Cards while a game is not in progress, just as it is impossible to have a Deck Problem (not including Decklist Problems) at that time. B has not indicated she is ready to play with her deck by presenting it to her opponent, so there is no deck we can evaluate for legality.
But wait, you might say, its round 3! She has been playing with an illegal deck all this time! Well, perhaps. I don't have a time machine to go back and do a deck check in the past, so it would be inappropriate to issue a penalty now.
I think this policy is great. It is entirely possible that a player can notice an error with her deck up to the moment they present, and it is important to let them fix that with no ill effect. The only thing different here is that she had some help noticing the issue.
Edited Dan Collins (April 15, 2016 09:34:41 AM)