re: Will CBS protect its sources if those sources are proved to have provided forgeries?
"I ask again: Is forging service records in an attempt to undermine a Presidential election a crime?"
No.
Now, the interesting question is will Rather protect this source. Someone giving you forged docs isn't really a source- unless you actually want people giving you false information.
I would think that as a reporter you might want to completely burn down the bridge of any sources trying to screw you- but maybe reporters have different moral standards.