The market was overpriced. Unless they can respond with equal upward pressure it'll still fall short of where it was. Greatly increasing liquidity and reducing margin requirements will only increase speculative activity like what lead to the bubble/bust in the first place.
They have the possibility of causing a short term rally to maybe even slightly prolonging the bull market, but it will need to correct eventually and this could make that correction worse. The main concern should be if the huge loss effects the underlying economy.