[Obi_Juan_Kenobi]

Much more likely, it seems, is that he's concerned about the blocksize debate and wants to come up with a sound technical solution. If Satoshi is smart, he understands that 'governing' Bitcoin is the greatest challenge. Removing himself from a dictator role was a smart move, but we're seeing some structural issues in the current leadership. If he did return, I think it would be to revisit how to navigate the future of Bitcoin.

If he wants to unload the coins, it's pretty simple: make a series of transactions that are time-locked to happen at particular intervals. Because other market participants know the coins won't be unloaded at once, but at regular intervals, there is no panic event. The selling pressure (and more importantly, the knowledge of the selling pressure) would affect the price, but not in a catastrophic event.

I also think people regularly underestimate the role of ideology in what happens to those coins. Not everyone is so motivated by a fortune that they'd risk their wonderful creation. The fact that they haven't moved yet is compelling evidence, though obviously precludes nothing.