Interesting bubble hand I just observed - Stars $1,000 SNG

[pokerlaw]

Just loaded up Stars, saw a $1,000 going so I opened it up: this is the first hand I saw:

PokerStars Game #2858913206: Tournament #14062205, Hold'em No Limit - Level V (75/150) - 2005/10/21 - 18:41:12 (ET)
Table '14062205 1' Seat #1 is the button
Seat 1: Button (3445 in chips)
Seat 3: SB (2830 in chips)
Seat 5: BB (4255 in chips)
Seat 8: UTG (2970 in chips)
SB: posts small blind 75
BB: posts big blind 150
*** HOLE CARDS ***
UTG: raises 250 to 400
Button: folds
SB: raises 2430 to 2830 and is all-in
BB: raises 1425 to 4255 and is all-in
UTG: calls 2570 and is all-in
BB said, "dfsfjsfdjokrldfsjkdsjkf"
*** FLOP *** [3c 4d 7h]
*** TURN *** [3c 4d 7h] [9s]
*** RIVER *** [3c 4d 7h 9s] [Ad]
*** SHOW DOWN ***
BB: shows [As Ks] (a pair of Aces)
UTG: shows [Kd Kc] (a pair of Kings)
SB: shows [9c 9h] (three of a kind, Nines)

Now....once the BB pushed, I assumed that UTG would insta-fold. My question is: do you fold KK here? what about AA?