SS doesnt need a premium hand. When in push or fold mode, SS have nothing to lose and all to gain, which makes them very dangerous. Especially on the bubble because even though the table wants the SS gone, nobody wants to be the one to take that chance unless a)They're holding a monster or b)their stack size is so big that doubling up the SS wont affect their stack and they can afford to take that gamble.
The bubble is perfect situation for SS to play more aggresive because you force your opponent to have a strong hand to call you with. I've seen SS push with hands like 7/10 suited and get called by hands as weak as Q9off and that player had an average size stacks. The SS doubles up and the Q9 caller is now SS. So, the tables can really turn in the SS favor. Even if they're still SS, they have more chips so when the push they put even more pressure on their opponent, even the chip leader. The SS might be 10% of the CL stack, so the SS can keep pushing and stealing the blinds. And even if the CL or anyone else calls, if the SS doubles up again, theyr'e back in game and now a bigger threat.