Isn't that a bit of a contradiction?
The assets are untraceable, but you know who owns them?
It's even worse if he doesn't! Suppose some mobsters figured out who Satoshi Nakamoto was. They kidnap him and demand he tell them the private keys to his millions of bitcoins. If he doesn't have any such private keys, he's in even worse shape than if he does. He has no way to get them to put the rubber hose away.