This [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...