I seem to remember that the novelization made it clear that Kirk requested personal command from Nogura because Kirk wanted command back. I haven't read the novel in a few years so I could be misremembering.
I don't doubt that. I haven't read the novel, but my understanding is that there are numerous differences between the film and the novel.
From the TMP novelization
CHAPTER THREE
“Jim, there is one starship that might be. . . positioned in time to pull off an interception.”
Kirk understood completely. But he kept his expression blank. Your next words could brand you a whore, Lori. Nogura’s staff whore. I hope I’m wrong.
“The Enterprise, Jim. There’s a chance they can get her out of orbital dockyards in time.”
“And?” Whatever Nogura had sent her here to say, he wasn’t going to help her with it.
“The commanding Admiral. . .”
“Meaning Nogura, of course. . .”
“Of course. He’s ordered everyone available from your old crew aboard. That will give Captain Decker the best. . .”
“Captain Decker?”
“Yes. You recommended they give the Enterprise to him, didn’t you? He’ll have the top crew in Starfleet, people already accustomed to working together. . .”
“And Nogura was worried I might want to take her out myself?”
“Well. . . no. Certainly, you’ll agree that the Enterprise has been so completely rebuilt and refitted that she’s not the same ship that you were so familiar with. Your protégé. . .”
“Decker.”
“Yes. He’s been aboard eighteen months now; he’s familiar with every change. . .”
“He knows the design changes, her new systems, like no one else in the Fleet could possibly know them.”
“That’s right, Jim.”
“Thank you, Lori. Mind if I close this console now? I’ve an appointment and I’m already running late for it.”
CHAPTER FOUR - The discussion between Nogura and Kirk reprinted in its entirety
“This must be rather difficult for you,” said Nogura. “Captain Decker has been something of your protégé, hasn’t he?”
“Yes, sir, but I don’t see how that makes it difficult. I’ve recommended him for jobs in the past because he was the best man available. In this case, he is not.”
Kirk knew himself to be motivated and determined as he had not been for years – and he had powerful arguments to use. The last five years of Enterprise logs supported his contention that Nogura’s greatest need was not a Captain familiar with a rebuilt vessel, but rather one with the greatest possible experience in dealing with deep-space unknowns, such as the one now hurtling toward Earth.
At first Nogura had seemed indifferent and impatient – but Kirk had seen the Commanding Admiral was also troubled and tired. Logs aside, was today’s Kirk a better Captain than the alert and upcoming young Decker? How much had Kirk been damaged by almost three years on the ground in an unfamiliar and unhappy environment? Ordinarily, Kirk would never have risked this direct a confrontation with the Commanding Admiral. But this was the first real challenge Kirk had faced in these past three years and Nogura, however dynamic and fearsome his personality, was also the man who manipulated him, used him. This was a battle Kirk was determined to win.
Kirk could see that Nogura was beginning to question the decision to use Decker, being unusually patient, incredibly so considering his reputation. It was becoming obvious that he must feel genuine regret over the way he had forced Kirk into flag rank.
Kirk had been with Nogura for twelve minutes. He had never known a visitor or a decision here to last that long. Then, he felt a chill as Nogura came abruptly to his feet.
“The entire staff considered this at length, Jim,” said Nogura. “I’m afraid every point you’ve made has already been carefully considered.”
“Admiral, these points were neither carefully nor properly considered since I was not present.” Kirk knew that his only chance now was to challenge Norgura directly. “And now that I am present, I submit that it is your responsibility to inform me of whatever negative arguments were made against my selection.”
As a flag officer and a member of Nogura’s staff, Kirk had both the right and an obligation to know of anything in his professional performance which his peers considered to be substandard.
Nogura’s eyes remained fixed on Kirk’s as five seconds passed, then ten. . . twenty. . . Kirk fought to keep the slightest expression off his own face. He sensed everything would be won or lost now in the next minute.
“How badly do you want her back?”
“The Enterprise? I can’t deny it’ll be pleasant to be back aboard her. . .”
“Jim, I am placing you on your honor. If there is the slightest chance that you are being motivated by anything other than professional considerations of intercepting whatever this is, trying to identify it, making contact with any lifeforms involved. . .”
“I don’t understand the reference to honor, Heihachiro. I don’t recall ever lying to you in the past – and I’m certain you never have to me.”
Kirk knew that he had won. He also believed that everything he had said or left unsaid was the whole and complete truth.
END CHAPTER