Whales are buying BTC in large quantities to move out of Gox. They don't necessarily need to cash out immediately. They could be holding BTC for speculative purposes as there is no other exchange that could possibly handle that volume (neither can Gox, that's why the price has moved so dramatically).
This is quite obvious when you see such large buy orders in 1 minute time spans vs a gradual move up in price.
They are buying BTC in large quantities to move out of MtGox, but they don't move it out of MtGox? Is this some kind of New Speak for speculative buying because they believe the price is going up?
Where did zeroblock argue that they don't move it out of MtGox? Sometimes it would be no disadvantage zu keep quiet.