I think the paternalist and machinating came from his having lived a very long life and having considered what would've happened if Kirk and Spock hadn't been together to kick ass and take names.

I mean, yes, it's possible the Horta and her baby would've been safely returned to each other. But perhaps not.

It's possible Somebody else would've pissed off Khan Noonian Singh, but would they have pissed him off as badly as Jim Kirk did?

Who could've gone back for a nuclear wessel vessel and saved the whales for the space people in the 24th century?

And that's just the first three examples that came to mind.