Bitter over Borrowed Burn - SILVER
Tyrone,
Thank you for explaining your thought process here. I, on the other hand, do believe this do fall under the upgrade path of the IPG, because the sideboard was discovered to be incorrect during the presentation period. A good swoop for a deck check will ideally be performed while the players are randomizing their opponent's deck. So yes, I would consider this and I would enforce a game loss here.
Also, I feel like when we (as judges) read the IPG, we have to assume the player is not cheating. If we suspect at any point while delivering a ruling that a player IS cheating, whatever category we are currently accessing for an infraction is throw out the window and we look at UC-Cheating. So I feel that every infraction was written with the assumption that the player was not cheating.
Also, I want to point something out. You said “ I feel like the philosophy behind it is that if Andy was cheating, the easiest time for his opponent to discover it is once Andy declares his deck is legal and ready to be shuffled, because in most games that's the only time you handle an opponent's deck.” I do not think this applied to the current scenario. Here we are talking about extra cards, which could be played in his deck, and that are extras not on the decklist and stored within the deckbox. It would be relatively easy for our player here to bring in these cards and swap them into the correct colored sleeve without an opponent having any kind of notice. And even if the opponent did have the deck into his hands, he could not find this error out as this relates to the front of cards he is not entitled to see.
Also, the IPG states “A window in which the error is a Game Loss is necessary to discourage intentional abuse. Once that point has passed, the opponent agrees that the deck is valid. Judges should always be mindful of the abuse possibilities when investigating these infractions.” I think this is the very window. The window where the decks are being presented, and therefore deckchecked, is the window we need to discourage intentional abuse.
So for all reasons stated above, I would give the player a game loss as per IPG 3.5 TE- DP. I would also request that he stores his extra cards elsewhere for the reminder of the tournament. If you suspect cheating, you could ask his earlier rounds opponent if they remembered him playing the said magma spay. But for the framework of this scenario, cheating is excluded.