An excerpt:
More fundamental, though, is that the theme of Kirk never facing death until he lost Spock just rings wrong on every possible level. I mean, we start with “Where No Man Has Gone Before,” where Kirk has to kill his best friend from the Academy. We move on to “What Are Little Girls Made Of?” where Kirk is deeply affected by the security guards who die, and while that consideration whittles down over time, to the point where he stops even noticing his crew dying by the late second season, Kirk has been seen to feel the loss of crew at least occasionally. Then we have “Operation: Annihilate,” where he listens to his sister-in-law die and finds the body of his older brother. Then we have “Obsession,” where Kirk’s guilt over his role (whether real or imagined) in the death of half the Farragut crew is so palpable that he devolves into the titular obsession to stop the creature responsible. Then we have “The Paradise Syndrome,” where he falls in love with Miramanee, marries her, and has to watch her die after finding out she’s pregnant with their kid.
And, the biggie, Edith Keeler, whom he stopped McCoy from saving. Yeah, that’s someone who’s never faced death. Sure. Hell, “The City on the Edge of Forever” was a classic no-win scenario: either let the great love of your life be killed or destroy history. And Kirk already faced it. For that matter, he took the Kobayashi Maru test twice before he cheated, so he faced it there, as well.