Well, if the feds do eventually produce the original tape and allow Ed's experts to scrutinize it, then it will be beyond reasonable doubt that Ed did actually have that conversation (unless Ed's experts can make a convincing case that the tape is not an original). But if the Feds ever do that, and if the tape is original and authentic, then what good will it have done Ed to be so intense about having his wife not cooperate with the AG?
If the Feds produce an authentic original tape for Ed's experts, then Ed's goose is cooked - he should have known that all along.
If he actually did have that conersation, then his only hope would be to claim he was "play-acting" or somehow didn't mean what he plainly said on the tape. I am assuming that Ed is not stupid, not uneducated as to how daming authentic tapes can be (irregardless of claims made by his wife), and that he wouldn't be wasting his time and energy on fruitless pursuits.