Oh, agreed on all that. I wasn't trying to suggest otherwise. But it wasn't curved for no reason. That takes extra effort in construction; I assume somebody wanted to imply
something, and (as with other details) I'm sad it's no longer possible to ask anyone who was there at the time about these kinds of decisions.
Now maybe they just grabbed the Pike/Charlie/Karidian/Brig wall like
@Maurice speculated, possibly because it was the best or only big wall handy and not already in use. But I doubt that setpiece was originally structured to be rotated 90°, and it would have taken some effort to adapt it for this use, cover the long shelf, insert the window, brace it against its own curvature for vertical use, etc. Either way, some effort and cost were required, so I generally assume it was for a purpose.
You may very well be right. For me it's not a great headcanon or screencanon fit, though.
- The room is depicted as being outboard of a circular corridor, and I always have trouble with speculative plans that try to shoehorn c-corridors into the secondary hull (most of the ones I've seen have no space for actual rooms on the outboard side, which is part of the reason I find them hard to accept).
- Kirk and Odona walk out of his quarters after, well let's call it Kirk's "medical infusion," and hear the banging sounds. Kirk gets a realization and specifically looks ahead down the Jefferies tube corridor, obviously with a destination in mind. They head that way, there's a camera cut, no turbolift ride is seen or implied, and they exit that corridor onto another one with all the typical trappings. As they enter a room with a yellow door across from the disposal chute, Kirk tells Odona this is a viewing port (certainly one of many scattered about the ship). Without a doubt he would have gone to the nearest one available, without wasting time changing decks, and surely there would be viewing ports on the same deck as the captain's quarters. So I find this on-screen evidence not very compatible with a lift ride or ladder climb down multiple decks.
- I was finding the in-world feasibility of this whole duplicate-ship mockup a bit easier to swallow when I thought they really only needed to build the saucer, or a portion of it. If the Gideons also built a secondary hull with windows, then they sure had to build the nacelles too.
Regardless of the intent or the construction realities, it's just a curiosity for me. It poses no problem for my project, since my model is of the
set rather than the "real" ship. I only have to deduce where the production team erected that room, and it appears to be in the swing area that shares space with the brig. (The disposal chute and yellow door are big clues.) Of course this is at odds with the fact that when they leave, they come out of the double-blue-doored briefing room

but it probably wouldn't have made sense to build the viewing port set room inside that room.