Originally posted by Lyle Waldman:

IPG allows for a “simple backup” as an option for any GRV, even one for which there is a prescribed alternate fix

Minor backup is described here:

Toby
In some rare corner cases, our default fixes produce unintuitive results. For example, I have an effect that tells me to draw and discard. I draw into an empty hand and play a land. Whoops! Applying the GRV remedy tells me to just discard now, but my hand is empty. That seems suboptimal, especially when fixing it is so easy, so we’ve added the ability to make tiny backups to fix an unnatural situation. How tiny? I’d say maybe one action that directly involved the affected permanent, where reversing it doesn’t affect anything an opponent would know about. In general, it’s better to apply the default fix, but the option now exists.

(Emphasis added)

Hello everyone, welcome back!

Thank you for an active discussion on this topic! We are really glad to see so many of you pitching in and voicing your ideas. As Talin said, “There's a surprising amount of variety in this week's responses!” and this is a good thing because it causes discussion.

Here is our solution:
As no extra cards have been drawn but rather, two cards were not returned to their correct zone, this is a GRV. All cards were drawn legally, the issue was in resolving the rest of the brainstorm, which rules out DEC. The fix for this problem is to have Anton put two cards from his hand on top of the library at this point and issue him a Warning.

The reason being the following IPG text:
IPG 2.5 Game Rule Violation:

If the infraction falls into one of the following categories, perform the fix specified unless a simple backup is possible:
If a player forgot to draw cards, discard cards, or return cards from their hand to another zone, that player does so.

With several card draws in the mix, in a format where most of the cards of Magic must be taken into account, this is not a situation that calls for a simple backup.

Nicolas did not have much time to either stop or even notice Anton was doing anything wrong, so we will not issue him a FtMGS.

See you soon in our next Knowledge Pool's scenario.

The question we need to ask is this: is the gamestate that occurs from the backup better than the gamestate from leaving it alone?

Attacking it from this way, I feel the answer is no; returning a card at random from Nicolas' hand to the top of his library feels like a punishment for Nicolas when he has committed no penalty; and even if we determine it was FTMGS that's still a very feel-bad fix. What if Nicolas wanted to do something after the Brainstorm resolved in Anton's end step and didn't have the opportunity to act, and we've now put the card he wanted to cast on top of his library?

We don't have a way to identify the card Nicolas drew for the turn either; if we did, the backup might be a bit more reasonable but I still wouldn't do it because of the information Nicolas gained off of his draw, plus the fact that we have our handy-dandy partial fix given by the IPG.