But at this point, if they end up having to roll it back, shutting it down would be pretty pointless - the initial damage has been done, and you can bet that they have a GM or two set solely to monitor the market for the time being to follow up on anything that needs following up on. Which, in essence, is the GM's job anyway. Not to mention shutting down the game would draw a lot of attention from people who genuinely don't know what's going on.
The fact of the matter is, a wait-and-see approach is probably more conducive to damage control than shutting down the game and announcing to everyone that one person managed to completely invalidate the free market system they tout so highly, especially in recent interviews.
The damage has been done. Those who were lucky enough to be in the right place and the right time with the right resources benefited for a very short time. Life isn't fair, we know.
There won't be a rollback, due to that every account that took advantage of that situation would have to be examined manually and adjusted manually, and I dont think OOO is willing to expend the manpower for that.