When gold crashes it gives people the oppurtuniti to buy low and sell high. When it is the Fed selling to JPM, they take the pain. That is what the Fed is for. To take the stress off of the major financial institutions. At the end of the day, it will be the Fed that is shut down. I would like to see JPM shut down, but that probably will never happen.
So when someone asks, 'Why would the Fed manipulate gold?' there are several answers. First, they have to. They use gold as their chief investment/asset. Second is the reson above. The lease gold to appease the other players; to keep the game going. There are many players in hot potato, until there isn't.