The government declassifies and disseminates information to the public from time to time, which is what appears to have happened here. They don't have to release the specifics of how it was obtained and journalists, although they can question it, don't have any recourse it confirming it, just like members of the public don't have the ability to know whether anonymous sources that journalists commonly use in stories can be confirmed. It is expected that public officials disseminate information accurately, just as it is expected by the public that anonymous sources used by journalists are accurate when cited in stories. Lee, having been a journo for decades knows this, but deliberately continues down the path of being argumentative because that's his known style.