This is the point I've been making since yesterday's "apology" that wasn't.
Saying "we can no longer vouch for the authenticity of the memos" is not at all the same as saying "we believe they were forgeries."
Dan still believes the memos are real, and wants viewers to believe it also, even if he can't prove them to be authentic.
You nailed it. But he cannot possibly REALLY believe they are legit. He is PRETENDING that he believes they are legit. Why? Partly to keep the slime on Bush alive? And maybe to make it seem like he is innocently an idiot?