You hit it in one. The June 28, 1966 "Final Draft" teleplay incudes the "Sorry, neither" line. It's not an ad-lib. (ETA: sniped by Harvey while I was drafting my reply!)
Blish adapted whatever version of the script he was given, and in some cases it was a very early draft. I'm pretty sure I read in the Ketterer biography that Blish didn't watch
Star Trek until it started running in the UK in 1969, where he moved in 67 or 68. So, his first four
Star Trek titles (
Star Trek,
Star Trek 2,
Star Trek 3 &
Spock Must Die!) were all written without benefit of watching the show.
Just wait until you get to the adaptation of "Operation: Annihilate!" in
Star Trek 2. It's a very, VERY different story.
I used to think that Blish had changed the storylines, but then I started reading through
http://www.orionpressfanzines.com/articles/unseen.htm, and discovered that Blish was working off early drafts, not rewriting them to suit his fancy. Apart from an occasional "easter egg" gesturing at his original fiction, Blish faithfully adapted the scripts he had access to, with allowances for how much he chose to leave out.