The devil....

....is in the details of the CBS document investigation.

. . . the documents appear to have been produced in Times New Roman typestyle. . . . Times New Roman was only available on typesetting and other non-tabletop machines until the desktop publishing revolution in the 1980s. Therefore [Tytell] concluded that Times New Roman could not have been available on a typewriter in the early 1970s and the Killian documents must have been produced on a computer. [emphasis added]

So what did the CBS investigation conclude?

So how did Thornburgh and Boccardi manage to walk away from their own expert's decisive verdict? The answer is hidden in footnote 16 on page 7 of Appendix 4:

"Although his reasoning seems credible and persuasive, the Panel does not know for certain whether Tytell has accounted for all alternative typestyles that might have been available on typewriters during that era."

If it looks like a duck....

(Hat tip to Captain Ed.)