I think this confirms what many suspected, Mapes is to be the fall guy. The information leaked to this reporter certainly puts all the blame on her.
Of course the "dog that has yet to bark" suggests that Rather and others at CBS are if not equally culpable, they are close to that culpability. They certainly dug in their heels rather than checked out their story when questions were raised.
Exactly, the network want to save Rather and Heyward.
You can't be the scapegoat if you're guilty as hell. Plenty of others at CBS deserve to be fired as well, but Mapes is by far the most culpable. Producers do most of the work putting together stories for TV newsmagazine shows. This whole fraud was her baby. Dan Rather would never even have heard of it if it weren't for Mary Mapes.