Bitshares can fix this kind of Mt Gox issue? the answer is no. for this case, the difference is DEX will never been frozen.
For example, let's try to imagine a scenario when ccedk cold wallet been hacked: their BTC/LTC/BTS... was gone, if you have ccedk issued UIA you will lost money, but if you have already traded the UIA to some other smartcoin or UIA which not belongs to ccedk you will survive. the worst case is that you didn't know about this and you still bought the OPENBTC, OPENLTC.....
so before reintroduce our DEX to other community let's think it twice, what kind of problem Bitshares can fix?