Questionable Move from a $6 Rebuy on PP?

[VespaRally]

It's down to the final four tables out of 460. In general, the table is playing tight (some walks, some stalling, etc.), but I have no specific read on the SB. I felt he was weak (having open-limped) and obviously I'm hoping he'll muck.
Without a real read is this just retarded?



Party Poker
No Limit Holdem Tournament
Blinds: t4000/t8000
(Ante: t200)
9 players


Stack sizes:
UTG: t41552
UTG+1: t155968
MP1: t304911
MP2: t103543
MP3: t143296
CO: t4359
Button: t107826
SB: t68804
Hero: t92343

Pre-flop: (9 players) Hero is BB with K[img]/images/graemlins/club.gif[/img] 9[img]/images/graemlins/heart.gif[/img]
7 folds, SB calls t4000 <font color="aaaaaa">(pot was t13800)</font>, <font color="#cc0000">Hero raises all-in t84143