I think the book is simply wrong about this. As you indicate, the scene in question never shows us the helm station
, only the navigator. I think the author simply mistook Budd Albright
for Bruce Hyde
It can't be that Hyde was sitting out of frame, unless the author is using words like "glimpse" and "shot" rather lazily.
The error is that Riley was always at the navigator
station in The Naked Time, not the helm. In The Man Trap, at 13m56s you can clearly see Bruce Hyde (or a Bruce Hyde lookin' dude) at the nav seat as the camera dollies past. This is the "chili peppers" scene.
I'm assuming the author had access to the daily call sheets that confirm that Bruce Hyde was present for that scene. Obviously, if he was visible, us fans would have known that for the last 47 years.