I read the letter. There isn’t even an official signature from the attorney on it, statements are legal documents, they should be signed.
So your theory is forgery? Unknown forger or do we have a suspect? Not perhaps that this letter isn’t actually a statement or a legal document, but a mere offer, and doesn’t require one?
Either way, forging documents from a well-backed law firm and then publishing them on your website seems like a recipe for getting sued out of existence. Why do you think the law firm is showing so much restraint? You think maybe they’re getting leaned on?
I can’t vouch for the authenticity of the letter but I believe that even under normal circumstances the agent of the firm that issues it normally signs it. The FBI/CIA/NSA may already be aware of what Flynn might know and his “offer” was rejected because they didn’t need him to make whatever case the info is in reference to.
Them being leaned on is a possibility especially with all that is uncertain at the moment.