But it seems to me like a casually unprofessional way for Starfleet to handle a change of command. The commanding officer isn't the first one privately informed, before any of his subordinates?
Yes, the whole thing was stupid. There were dramatic reasons behind it, but it really doesn't hold up to much scrutiny.
It's discourteous to Decker, clumsily handled and perhaps unwise. But unprofessional? No -- it's well within the jurisdiction of an Admiral I should think.
Anything that is handled in a way that it negatively impacts the command could be considered unprofessional. Allowing the news of the change of command to be distributed among the crew before the "outgoing" CO is informed is, really, appalling. Immediate assumption could be that Decker had done something wrong. It should have been done more like this:
- A superior officer who is not Kirk informs Decker privately of the decision and the reasons.
- Kirk and Decker meet in private and make arrangements. Preferably they bring the department heads in and brief them; presumably there was also an assigned XO who was also affected.
- The entire crew is informed of the change.
Of course, there was an emergency and so on, but all the meetings could have been done in minutes.
Interestingly, in another Robert Wise movie with a displaced ship's captain,
Run Silent, Run Deep, the "bumped" captain was informed personally by the squadron commander in a scene more like the one when Kirk tells Decker in engineering. He then goes to the "new" captain's house to discuss it in person (and more dramatically).
Decker's demotion never should have even happened. Admiral Kirk could have been placed in charge of the mission, with Captain Decker running the ship.
Exactly, just like in the very next movie.
Additionally, it's very hard to believe that a commissioned rank can simply be taken away without some kind of judicial procedure. If the Federation President, Council or whatever commissions officers, why would Kirk or Nogura be able to override that in a matter of minutes? Doesn't make sense.
It wasn't a demotion...
It's merely a formality - when another senior officer takes temporary command of a ship, and the official CO is still on it, they are "demoted" (in brevet form) to Commander instead of Captain.
"Grade reduction" is the same as "demotion" in rank, even though temporary. But that isn't how things are done, in real life or in Star Trek, as seen in the later movies. Officers command others of the same grade all the time, everyone knows who is senior and it doesn't cause any problems.
It's basically the same thing as a brevet (temporary) promotion to Commodore (or any temporary rank).
That's not what a brevet promotion was, it was an honorary increase in rank title given as an award, without any increase in authority.
By the late 1970s Commodore had gone out of use in the US Navy and Kirk being an Admiral might reflect that change. In Gene's 1970s Trek there might not be any Commodores anymore, just Admirals (like the present day Navy).
Of course there weren't commodores in the US Navy in the 1960s, either, but TOS had them.