Misdirection.
He simply claimed the assertion that the font didn't exist, and the capability to do superscripts, as of the date of the memo weren't accurate.
He's setting us up. (or so I speculate)
Too complicated.
Even if everything in the memos were true, I still don't see anything that would be fatal or even damaging to Bush. Nothing makes him a liar and there isn't anything that can't be explained. Certainly, it gave the Lib's something to rant about, but that's about it.