Bitcoin isn't anonymous at all. It's at best pseudonymous, but even that is pretty easy to break. There are companies who do nothing but provide analysis services that link real people to bitcoin addresses.
Chainalysis does it all the time.
Satoshi left the scene without ever cashing anything out, and before blockchain analysis really became a thing. He's not relevant to modern bitcoin at all outside of having been a founder of it a long time ago.
If he were spending bitcoin today, he could be found and identified easily, which is likely why he (actually the conglomerate that posed as him, Satoshi isn't likely a person) left once he achieved his goals.