alt Hacker NewsThis [1][2][3] seems to have a methodology for identifying Satoshi's coins, mined from 2009 to May 2010. But yes, for coins mined after May 2010, he likely can spend without scrutiny.
>The idea that if his coins move everyone would panic is a post-2015 idea
Here are 2 people in 2013 expressing that idea: [4][5].
[1] https://bitslog.com/2013/04/17/the-well-deserved-fortune-of-...
[2] https://bitslog.com/2013/04/17/more-on-block-mining-history-...
[3] https://bitslog.com/2013/04/24/satoshi-s-fortune-a-more-accu...
There's ambiguity here. When people talk about crashing the market they mean if he attempted to sell every last coin he owns for dollars all at once. Of course that would be a signal of lost confidence. What I mean is the more likely scenario of spending coins to achieve some specific goal or project.