[SumZero]

I'm always skeptical of intuition around questions of probability but my gut says that it is, at best, only a slight difference. My gut says no difference on the probability someone else holds AA but I'm not sure as there is a slight difference in the types of cards that are dead.

The reason is in the three fold case all you know is that the three players who folded didn't have paired cards and 6 cards are dead. But the six cards that are dead are all of equal probability of each type of cards. The only thing you can really say for sure is that there isn't a single number card that is dead. I.e., not all the 6's are out as 4 6's can't be dead in 3 hands without someone having a pair. And that the 6 cards are slightly more likely to be all different as if two were the same then there is a small chance that the two that were the same were in the same hand and were a pair. But I don't think this effects the number of ways AA is going to be behind you. And it certainly shouldn't materially effect the number of ways AA is going to be behind you.

Of course if you changed the robots to also open with AK-AT now their folds are biasing the hands towards slightly more A's being in the deck still to come and a slight increase in AA behind you.