How can someone become "Commissioner" while being that much of an ass?
Honestly I don't think he was. He was genuinely concerned about the health of the plague victims in the New Paris colonies:
FERRIS: I remind you, Captain, I'm entirely opposed to this delay. Your mission is to get those emergency medical supplies to Makus Three in time for their transfer to the New Paris colonies.
KIRK: No problem, Commissioner. And may I remind you that I have standing orders to investigate all quasars and quasar-like phenomena wherever they may be encountered. Besides, it's three days to Makus. And the rendezvous doesn't take place for five.
FERRIS: I don't like to take chances. The plague is out of control on New Paris. We must get those drugs there on time.
KIRK: We have until 2823.8 to continue the search, Commissioner.
FERRIS: You don't really think you'll have any luck, do you?
KIRK: Look, these people are my friends and my shipmates. I intend to continue the ship's search for them until the last possible moment.
It's like "The needs of the few outweigh the needs of the many" for Kirk, while for Ferris it is "The needs of the many outweigh the needs of the few".
We are biased on behalf of our characters, while Ferris looks at the big picture and rather sacrifices 7 on behalf of 70 or 700 plague death victims, IMHO.
I think right from the start Kirk is somewhat too over-ambitious, that Quasar wouldn't have gone anywhere and there'd be a later opportunity to study it. And once things went south, Kirk would have probably been the one responsible, had they not recovered the survivors.
At least he immediately ordered "Warp factor one" after the Galileo
survivors had been aboard.