It's a Catch-22 situation.
If the documents are genuine, then the source is covered by First Amendment privilege.
If the documents are fraudulent, then there is a federal felony involved, and CBS becomes an accessory.
The only way to avoid a legal nightmare is to insist that the documents are genuine in the hope that nobody can prove conclusively otherwise.
Bingo!!
There is NO WAY to conclusively prove these are forgeries. You can speak to motive all you like, but it is still just supposition.
See-BS can simply say "the originals in our possesion were composed on a word processor, but that was done by the good Colonel himself in order to preserve his collection of hand-written personal notes (of which he had many, per his widow)".
I think this whole affair will be a lot like peeing in a dark suit: it gives you a nice warm feeling, but no one else really notices!
There is no such privelege in the 1st ammendment.