This scenario might make sense if they hadn't made the mistake of adding a signature to the memos. If they now claim all they had were handwritten notes, they also admit that they forged the signatures on the memos. It is is still forgery either way, and harder to justify or explain under this scenario.
If they were handwritten why the header information on the type written memo's in question? The easy answer is they weren't handwritten.
They cant -- or shouldnt be able to claim the documents are handwritten -- else why didnt they just produce the "handwritten" documents to begin with?
The signatures might be digitally scanned images from the original "hand written" memos, which they transferred to the "typed" replicas.
It would explain why they relied on a guy who is a signature expert, not a "document" expert, and why they only showed him examining the signatures and proclaiming them legit.