I don't understand this. If I were CBS, I'd be raking over the coals whoever gave me the documents. If it turned out that the memos were in fact forgeries, and if thie person had been used as a source previously, I would be assigning reporters to double-check the veracity of any news stories this source had been used for.
I know CBS has held at least two high-level meetings regarding this matter. If I were their executives, I would at least put out a statement that CBS was having a thorough independent investigation of the documents be performed. The military officer who supposedly wrote these memos is conveniently dead, but his family think the memos aren't genuine. That alone should be raising some questions; never mind the question of the typeface used.
This just makes CBS look really, really incompetent, that they aren't (apparently) even questioning these documents. If they're forgeries, it would be better to admit to having been used and let the truth come out, than to act as if you're doing your level best to delude yourself. Whoever their source was, he or she doesn't deserve the press' protection. If I were still in journalism, I'd give this dweeb the back of my hand.