Can you explain this preflop AA limp-fold (!!!) ?

[Matt Flynn]

This is a real hand, presented exactly as it happened save for one fact. I was there. Happened Saturday night.

It's a NLHE tournament, roughly $8,400 pool, 27 players started, 20 remain, average stack size is 3,200, blinds 100-200, no ante, table is 7-handed. All fold to 2 off button who limps. He has 2000 behind. Button lightening-quick goes all in for 2000 straight. Guys in blinds fold. Back to limper, who thinks and thinks and finally lets go. Button shows AKo. The limp-folder had - and mucked - pocket aces.

Cutoff (who does not know any of the players at the table and had not played with them before the tournament) says to limp-folder doesn't matter, made no difference what he had, what the hell took him so long to fold.

The cutoff was David Sklansky, and he was not joking.

Can you explain the fold AND identify the one incorrect fact? (Note: he did muck the aces correctly, and all the numbers are correct.)