You assume that's what it was. Calling the bounty in the headline ~$6,000 is disingenuous, too, because dumping the BTC into the market would drop the price significantly. You'd never be able to move it for $6,000, currently. You're talking about more than the daily Mt. Gox volume.
It's actually hard to say. Mt. Gox order volume is partly hidden because of dark pool order. What people see might not be an indicated amount of bitcoin on the market.