And, anyway, unless someone finds an old memo from the Desilu days that addresses the name change, then there will always be doubt about the actual reason, especially since Roddenberry's stories tended to change, and memory is fallible.
There'd be no need for a memo, because as I keep saying, it's just the sort of thing that happens in the early, rough stages of a creative process. Let's be clear here: It's not like Roddenberry ever committed to the name Yorktown
. It's not like he sold the series with that and it went into production under that name and then some big significant thing happened to change it. It was in one
document, the very first thing he ever wrote down about the show -- a typewritten document that's full of spelling and punctuation errors, names the captain Robert April and the navigator Jose Ortegas, says Spock is "probably half Martian," says the time frame is somewhere between 1995 and 2995, says the ship "will rarely land on a planet," etc. The name Yorktown
doesn't appear anywhere else, ever, except in this one document that's clearly extremely rough and tentative and that contains a lot
of things that were very quickly changed.
So that kind of name change that early in the process is so routine and normative that there wouldn't have been a need for a special memo to explain it. Especially since memos are for communication among the production team and the name was evidently changed before production began.