Anyhow, I don't remember those typewriters being used that much back in the 1970s and I'm reasonably sure the military didn't have anything that sophisticated. For all I know, they could have still been using manual typewriters.
Proportional spacing doesn’t matter.
It was what was in the memos that was conclusive as to their fraud- anachronistic entries, wrong acronyms, lack of knowledge of pertinent regulations.
CBS role in the investigation was to protect CBS because there were criminal liabilities if CBS proved definitively that the memos were frauds.
Hence the CBS claim that the memos could not be conclusively proved false.