Thanks for looking those up Harvey
. Your reputation as the go to guy for this stuff is secure
I'd say you're probably right, it was likely a done deal that it wasn't going to happen (the pickup of the last two), and someone had communicated this to Freiberger, who decided to keep the news of the cancellation away from the cast so they could get the best product out of them as possible in the circumstances.
You'd *think* that by now production sketches of an aborted episode 25, or a "I was set to appear in Star Trek, then they cancelled it" story from an actor would have cropped up by now if any serious work was done, but who knows.
One thing I have learned about TOS is never count anything in or out till you see it in a memo!
Sometimes you hear Shatner was set to direct 25 or 26 - myth or fact?