In Corbomite Maneuver, this bizarre conversation occurs:
Jim and Bones are drinkin', chillin', and chattin', and they are relaxed and happy - enjoying a break and a bit of each other's company. Suddenly Rand enters, bearing a salad plate for Captain Kirk, and the mood in the room becomes tense. Rand over-solicitously tries to serve Kirk, and Kirk complains, and rejects her attention rather impolitely. Finally he dismisses Rand and she exits. Then Kirk complains to his friend McCoy about Rand:
Bones and Jim, drinking, and talking, happy together
Jim's not happy with what Rand brought him
Jim's unhappy with Rand's super-helpful performance
Jim just plain doesn't like Rand
Jim just plain doesn't like Rand's GENDER
Bones can't resist the urge to tease Jim a little
Jim is NOT AMUSED
Jim explains why no woman has a chance with him...
...because he's too busy worrying about the ship to worry about a girlfriend
Bones wisely says nothing
Jim's one complaint about Rand is her sex. He apparently would have chosen a male yeoman if the choice had been his. He clearly doesn't like Rand, but his one reason seems to be because she is female.
Is it really necessary for me to point out that the average heterosexual male would be delighted to have a pretty young female yeoman, and they probably would think that Kirk is nuts?
He's not nuts. He's not even unusual. He's just Gay. It really is just that simple.