As far as I could tell, the player that still had cards was not at fault. The dealer and mucker acted very quickly before seat 1 could do anything. My guess is that both the dealer and the mucker may have simply forgot someone was sitting on the other side of the table, and once the player to the right of the dealer folded, it went "push-muck" right away.
Nick - I see your point. And you are right, if this was a cash game situation, we definitely would have more leeway. I am pretty sure the decision is "standard" now (correct me if I'm wrong), for better or worse. As I'm sure you are aware, more and more responsibility is being put on players now despite dealer error (accepted action!)

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But maybe there does need to be further consideration on this one since there is an element of dealer error here, with a dealer prematurely pushing the pot. Let's think about this one a bit. I think a few issues need to be addressed here:
1. While it is true that we are killing seat 6's hand, and that is a crappy reason to kill a hand especially since the dealer induced the error, if we allow seat 6 to keep the pot, then are we not effectively killing seat 1's hand? Seat 1 hasn't done anything wrong. Now if seat 1 was hiding her cards, and that contributed to the error, then you could definitely take that into account. But if there is no evidence of that and she was just sitting there,
with cards in plain view, and it was her turn to the act as BB, she looks down at her cards and hesitates for a moment to consider her action - yet meanwhile the dealer has pushed the pot -- on her turn-- and seat 6 happily grabbed the pot, what makes seat 6 "more" innocent than seat 1 here?
2. Does it matter that when you come to the table to make your decision, that seat 1 is the only player with live, identifiable cards?
3. Are you going to dig through the muck to search for a hand that has not been tabled? Do you take the word of seat 6 that she will accurately tell you the cards that she has? What if she tells you which cards that she has and you cannot find them in the muck? We've been through this whole issue before, and no one goes through the muck any more.
4. The problem is that we potentially have two innocent parties here that have both been screwed by the dealer. Therefore, I have to ask: Who is in a better spot to protect their hand?
You open the action with a raise in late position, and hope to steal the blinds. It's late in the tournament, blinds are big, you are hoping that everyone folds. The button folds (yes!)... the small blind folds (whew!)... you look over at the big blind and hope he folds as well... you wait silently as the big blind peels up his cards... meanwhile you notice that the dealer has pushed you the pot!
Are you taking this pot, or do you say "wait, the big blind hasn't acted"? Unless the big blind is hiding cards, I find it much harder to accept that the raiser, who was attempting a steal of the blinds, was not paying attention to whether the blinds have folded. And if she wasn't paying attention, IMO, she ought to have been. I have to consider the (in my mind, much more likely) possibility that the raiser knew full well that the action was not yet completed, but accepted the pot anyways to try to "force the win". I call this "willful blindness", and I don't think it's something that we can reward.
5. Is there any merit to the argument that in a situation analogous to the skipped player situations that we have been discussing, that the dealer and seat 6 are essentially "acting out of turn" here, and that seat 1, who is acting in turn, may be worthy of protection rather than having her hand automatically killed?
I think it's this last point that perhaps may actually be the strongest argument for those who favor letting the raiser keep the pot. Seat 1 does have an obligation to preserve her right to act if she is about to be skipped. There may be analogous "skipped player" situations, some which give the skipped player the benefit of the doubt if not enough time has passed to stop the action, while other suggest the hand may be ruled dead. For example, if the dealer makes a mistake and prematurely deals the next board card, the rules allow for the action to be completed and the board card to be redealt. Is this an analogous situation? Alternatively, if the dealer prematurely deals the next board card and there is further action, then many TDs will rule that the skipped hand would be dead if there was an outstanding bet that had not yet been called on the previous street. Is this similar?
I think on balance, unless the skipped player is hiding her cards, I personally think more of the fault has to lie with the raiser here -- unless there is some way to give skipped players more time to speak up. It's too bad we don't get dealers to announce something like "last chance to speak up before I award the pot", before pushing the pot.
Would anybody consider an even more creative solution... e.g. would you consider looking at the Big Blind's cards and trying to determine if they may have folded?