They could buy bitcoins on gox at gox prices, then unlike anyone else, could arbitrage by transferring those coins out and selling on other exchanges.
Of course there are coins to sell on gox, up until they halted trading, all trading is just shuffling their internal ledger, they didn't need the actual hard currencies underneath. (Which is why they should have been siloed, both the 780k reported missing bitcoins but ALSO the less highlighted 30m deficit on USD. (which is in part critical to show it wasn't just tx mallebility or btc problems, it was general bad accounting))
If the presentation is to be believed, there are only 2000 actual coins at Gox, and Gox already controls them. Gox already can transfer them out and sell at a higher price. (The low round number balance suggests they've already been doing that.)
Meanwhile, there are 624K+ phantom coins listed as being in customers' accounts. So you can't (honestly) attract new "long term, high leverage" investor/trader fiat cash with the idea "there are cheap real coins here for you to buy then transfer out at a profit!" No one gets any new real coins by shuffling phantom coins around, and Gox needs all the real coins for themselves. If any real coins go to others at low prices then Gox becomes relatively more insolvent, not less.
And for as long as the arbitrage opportunity exists – phantom Goxcoins are selling for way less than real coins – who would be foolish enough to transfer new real coins in?
Of course there are coins to sell on gox, up until they halted trading, all trading is just shuffling their internal ledger, they didn't need the actual hard currencies underneath. (Which is why they should have been siloed, both the 780k reported missing bitcoins but ALSO the less highlighted 30m deficit on USD. (which is in part critical to show it wasn't just tx mallebility or btc problems, it was general bad accounting))