I think it is only rumors and no one really knows the exact amount of Bitcoin that Satoshi Nakamoto has, that one million prices of Bitcoin is only a rumor and there is no solid proof about that. I guess most of the people think that he owns a lot of Bitcoin it could be true or not and he is the only one who knows about that information.
I doubt he Will ever use those coins. He probably already destroyed those private keys and they are now lost.
He probably has a personal stash of his own, that he mined without any correlation to his "Satoshi" identity
There is a possibility about that but destroying the private keys of those wallets does not make any sense or it can make sense if it is lost forever.