I have no doubt you're correct. If anyone told me that they'd mistaken Ted Knight for William Shatner I'd have thought they were nuts too. But I'm listening to it again. The thing that got me: In the transporter room Winston sounds like he's talking in an intentionally higher voice. A far cry from Ted Baxter. In this episode at least Kirk's voice is deeper than Winston's.
When I was listening the other day I did think that his voice became less "Shatner" as the episode goes on. I figured they recorded it in more or less one take and Shatner got better as he went. Orrrr he was just Ted Knight all along.
Now I've listened to an episode I didn't think I liked very much twice in two days. It's much better than I recalled but I'm still going with One of Our Planets is Missing.
Hey at least I always knew Balok was Ted Cassidy despite what the Star Trek Compendium said.