Not really.
The FDIC is already on the hook for all the losses. This way they get close to what they think the garbage is actually worth instead of the pennies on the dollar they'd get from a fire sale.
tl;dr: "backstop" in this instance basically means "if the steaming pile of hot shit no one really wants that you just bought at a discount is worth less than what you paid for it ... we'll make up the difference."
