I think it’s an earlier episode than “Miri”, but the one where they get infected and everyone is doing stuff because their barriers are down (drunk), Kirk mentions in his breakdown before Spock kicks sense into him the ensign that he sees every day, but can’t do anything. So there was the thoughts deep down, but Kirk has disciple and morality. Even more so in the novel version, Kirk is a prodigy in most canon books and wouldn’t do that stuff.