Just don't store (the majority of) your coins on exchanges (for very long).
The 'for very long' thing does not matter. Just FYI. The exchanges pay out until the very second they don't pay out. If you think you will just move quickly through that, you could easily get your coins caught. And I wouldn't be surprised if a near-fail exchange can see big movement real time and selectively halt anything they want.
Yes get your money the hell out of any exchange as quickly as possible, but that's not a secure trading method.
This is a major weakness of bitcoin right now. There just is no safe way in and no safe way out. Almost completely Illiquid.
There wasn't $300M worth of assets actively trading on MtGox the day it shutdown. If the only people who had funds on MtGox were those actively trading or those in the process of making a conversion MtGox would still have failed but the size and scope of the loss would have been magnitudes smaller. The negligence or malfesence by MtGox was amplified because you had people using it was a wallet and even a form of long term storage. Lots of reports of people who had coins marked there for months, not trading, not withdrawing just sitting there like some (very insecure) safety deposit box for Bitcoins.