OK, let's reverse the roles.
You have 4k in the bb on the bubble, and the sb goes all in, and has you covered by 2k. He hasn't really gotten out of line, and has shown down solid hands, but has also won many hands w/out showdown.
What is your range for calling off all your chips here on the money bubble???
If Im reading betweem the lines of the HH history correctly and there are $50 blinds, the push is offering BB something like 1.33:1 odds. He should be putting you on a pretty aggressive pushing range...something like top 33% of all hands, and if were TC odds only to worry about would take something like top 40% hands to call. Since we are on the bubble he may tighten up to matching your expected 33% range, which is still a pretty big range:
55+,A2s+,K4s+,Q6s+,J7s+,T7s+,98s,A5o+,K8o+,Q9o+,J9o+,T9o
Since nobody is getting that precise at the table round it 55+, Axo, Axs, K8+,QT+. Thats around 28% of all hands.
Edit: calling this a SnG is a little bit deceptive. The money bubble in a 3 payout SnG is huge...bubbling out really hurts ROI when its at the expense of a 20% payout that can grow to at most 50% (2.5 x sneaking in)
Here you are talking about an 8% payout that can grow to 37% (4.5x sneaking in). Gambling here makes a lot more sense than in a SnG for both the raiser and the caller.