He may have been doing whatever whenever, but the scene as cut into the movie was fine--could have been used and it would have worked. They cut it for another reason.
It's no secret that they only put the scene in the script as the final tempter to get Takei to sign a contract. He had held out till one day after principal photography started, IIRC. He said if the role was a repeat of TMP, just sitting and piloting, then he wasn't interested because Sulu would have moved on by now. It has been suggested that Bennett and Meyer were never really serious about keeping the line in, but there was still hope - and the vague promise that future ST films might have meatier roles. George often says that the actors always took each ST film one at a time; they assumed each one was "the last one".
But... you said "NO Shatner did not botch it on purpose"
and Takei himself told me - in 1984, at his house - long before he started mentioning it at conventions or in his autobiography - that Shatner deliberately did his renowned Shatner trick (which often meant that the only usable take is a Shatner closeup rather than the other person in a scene). So if that makes George a liar in your book, so be it. He seemed genuine enough at the time and it wasn't onstage bravado to hundreds of amused fans, it was a quiet chat over green tea.
I guess it's a blessing to do a scene with shatner and not have to look at him!
Perhaps George was trying not
to look at Shatner, who was off-camera crossing his eyes or doing bored-face.