If they open for trading but there's suspicion they're no longer fully solvent, withdrawing BTC will be the fastest exit. BitstampBTC may therefore trade higher than other market's BTC IOUs.
What if the hacker sells the 18k BTC on Bitstamp? (if they're stolen)
his plan then is to buy xrp and then
if there are 18 k stolen coins the thief will for sure not go to an exchange which operates under KYC