Spock: I would posit that, in this present, you were never injured in the training accident, thus you remained captain of the Enterprise, putting you in charge at a crucial moment in the ship's existence.
Spock is engaging in supposition based upon his impressions of the accident from the mindmeld. Spock's suppositions are not necessarily accurate in all respects. Pike's vision of the future given to him by the Boreth time crystal may not include "future memories" of having been promoted to Fleet Captain or having turned over command of the Enterprise before the accident, only the incident, the cadets involved, and the horrific outcome to Pike, himself.
Nothing requires a fleet captain to give up command of a vessel. The chronology can easily accommodate Pike keeping the Enterprise OR taking a new ship, with a third option of no promotion for the specific purpose of a glimpse into an alternate future not intended to actually occur. Given that no time travel story survives close scrutiny, it’s best to go with the flow. Helps keep the blood pressure down.
It doesn't work even as supposition by Spock, though, and the chronology can't actually accommodate it, much less "easily."
Why not? Because we know from Spock's dialogue in "Menagerie" that he served under Pike for 11 years, 4 months, and 5 days, and that the events of "The Cage" were 13 years ago. So, even if "The Cage" were Spock's very first mission under Pike (we know it wasn't, but let's say), that's a difference of 20 months.
We could try to fudge that a bit more... but even if we assume—since Spock's not being more precise about the 13 years—that "Menagerie" is very early in 2266 (notwithstanding that it's seven episodes later than "Balance of Terror," which this episode of SNW tells us is also in 2266), and that "Cage" was very late in 2253, so 13 on the calendar is only, say, 12.1 in time elapsed, that's
still a difference of at least nine months.
Yet in this episode, Spock says the accident was just six months ago.
IOW, Spock ceased serving under Pike a bare minimum of 9 months earlier—more plausibly about two years earlier—when Pike was promoted. Spock stayed with the ship, and Kirk assumed command. The accident had to come later. Spock would not and could not make any suppositions to the contrary.
Plus, as I noted upthread, when asked in "Menagerie" if he'd met Pike, Kirk said that yes, they met when Pike was promoted. If Kirk had inherited the ship from him due to the accident, then that remark would make no sense. Starfleet would have no reason to promote Pike
after the accident... and even if it did so (just as some sort of "honorary" thing), Kirk would have
known about Pike's injured status, so he couldn't possibly have been surprised by it.
If Pike's motivation for keeping command was somehow connected with avoiding the accident, then someone in this story could and should have said so. Otherwise, the internal logic falls flat.
And proclaiming that no time-travel story makes sense anyway, so we should just roll with it, not only gives the writers a very generous free pass but literally undermines the whole point of the episode. Some time-travel stories actually
do have consistent internal logic. This one really should have.
