I'd surmise that there's a lot more than mere "distress" and "concern" at CBS. Righteously PO'd at Rather is probably more prevalent. He's besmirched the entire organization.
Yes, I'm sure they're PO'd. Not because he lied, but because he got caught lying. Even worse, he gave conservatives a word that's hard for the "professionals" in the MSM to laugh off, deny, and ignore: forgery.
Even if you are pissed, you have to say you're distressed and concerned in order to keep your job when it comes to The Dan. Just look at what happened to Berne Goldberg when he publically pointed out what everyone knew about leftist bias.