I think the reason BLATHER is digging in his heels so hard is because he knows it came directly from the DNC and if he blows that, then not only is he toast, but so is his precious pretty party. He has to cover this with his life.
CBS fall into a pile of crap and ABC will not help clean them up.
You're absolutely right.
If Dan Rather implicates the DNC in the memo fraud, the danger to him may extend well beyond simple career considerations.