The only thing about this episode that rings false for me is the reveal of Spock's parentage. We're led to believe that:
a) Kirk, knowing how Spock/Vulcan's value privacy and also ingoing how out of place it is, asks Spock in front of the just arrived diplomats if he wants to go visit his folks. This is just a very awkward way to get to the hook.
and
b) Kirk doesn't know that Sarek is Spock's father. The captain of the ship, who calls his first officer his best friend, has no idea the Vulcan ambassador and his human wife are Spock's parents. Kirk never read Spock's dossier when he took command? It's not common knowledge? Are there so many Vulcan/human couples that Kirk never even got suspicious? Spock even once said, "my mother is a teacher, my father an ambassador." Kirk looks like an idiot all around, just so we can get to the big shock and loud music fade out.
Other than that, super episode all around.
Good point. I really don't have a good answer for this.
I'm just going to say, it does reinforce the fact Mr. Spock is a private person, he mentioned that information about his parents while under spore influence, and maybe Jim wouldn't pry into personal history of his crew unless it was mission required. And when would that have been mission required?
And one of the Beatles was working for Sarek and they didn't even mention it.