This cannot be ruled out with absolute certainty. It is just highly unlikely. The font (a variant of Times Roman) and the machine to type it (IBM composer) did exist at the time the memo was allegedly produced. But exact match to MS Word is suspicious. The poor quality of copy is suspicious. The only way to be sure is to examine the originals. Let them produce the originals!
It's going to come down to character spacing. Someday soon someone's going to use something like Fontographer to open the font, write down the character widths, numerically figure out the width of the text according to the font, and then check the copy. Then do the same thing with the IBM composer. The forgery won't be all that hard to prove, it will just take a little bit of leg work. I worked at a printing company for many years (and even made fonts) and doing something like this is tedious but not overly difficult. I only wish I still worked there--I'd have the tools and could do a thorough analysis in a day or two.