Satoshi's wallet isn't locked and he isn't dead, tomorrow he could even dump 1M coins and you know what ? No one will care.
Why someone with the most advanced and revolutionary Blockchain tech would dump the premine ? Where is the logic ?
Its cute you think people are logical lol Thats going to bite you in the future. People were concerned about Mt Gox Trustee unloading 400 million an blame that for bitcoins price drop but you're right someone dumping 8 billion dollars worth on the market would be totally fine lol.
What I did hear though is no reasonable explanation for it not being locked.
Since when this kind of volume is sold on the market, the biggest are always sold OTC. (Out of The Chain).