It occurs to me that in the early '70s I actually used a Selectric Composer. We put out a newsletter. We had to travel to the office where we were allowed to borrow the machine, which was prohibitively expensive.
There is no chance that a National Guard officer, typing soi-disant "CYA" memos would have access to one, or, if he did, would bother to fire it up for this purpose. This is all the more true, because, if for some chance he were playing with one, he'd do something more interesting and elaborate than the memos we see.