That's a very interesting proposal. Just as the miners have an incentive to protect the integrity of the blockchain, they also have an incentive to bolster public confidence, and a "community bailout" via 51% consensus could do that.

On the other hand, it would uncomfortably remind people of the power that belongs to the miners (and particularly, the mining pools). It would open up the possibility of attepting to build political coalitions and proactively voting on blockchain policies (which might be inevitable anyway). It would also create a deep moral hazard, incentivizing future risky behavior from big actor, who then seek "bailouts", just like the conventional banking system that crypto-anarchs are trying so badly to differentiate from.

I wouldn't expect the community to do such a thing, but at the end of the day, the miners decide.