$5 SH SnG reraising allin+caller

Just curious about thoughts on this subject. Bubble situation where someone goes allin and gets a caller. When do you call too. Or reraise to push out the other caller. At the time it felt irritating that someone did this, but... what are the times when it's proper?

Specifically...
UB 6-seated SnG $5.5 buyin. 3 players left. All reasonably solid players (at least in appearance to this newbie).
Blinds 20-40
Me Button ~3000
SB ~ 4500
BB ~ 1500

I raise my standard 150 with 99.
SB calls
BB pushes allin.

I'm figuring him for 2 or even 1 overcard, so...

I call.
SB pushes allin.

Ugh! Can't we cooperate to knock this guy out? I'm covered, so I fold.

When is this the right play? Sure, if he had AA/KK it makes some sense, but.. what else? Even then, isn't getting the bubble popped better? Or does chipleader have a different view on things (not THAT big a chipleader though).

I'll post the showdown in a few hours/posts from now.

--Matt