Dan, the report you've been reading is obviously a forgery. If you read the real thing surely you'd sack up and resign like a man.
Before Rathergate: I am a hard-nosed REPORTER, I do journalism, I don't just read the stories like a bimbette.
After Rathergate: Not resigning implicitly means I am a bimbette (or just a pretty face, or Ted Baxter), I take no responsibility in the story.
Of course, even had he offered to resign, CBiaS would have begged him to hang on for another few weeks, because firing his ass (or him leaving) would basically mean the last 30 years of CBiaS news were mostly baloney not just the Mapes story. So they'll live with him for another few weeks and protect his derriere.