Ah. It's been a long long long time since I've seen the original episodes. I think maybe the last time I saw them was in 1988 or 1989 in college. (So about 20 years). So I have a really vague memory of Kirk and Uhrua sort of kissing, but I couldn't remember if they were being manipulated into it or if it was voluntary. I do vaguely remember that they traded looks and she did have affection for him, but nothing major.

At any rate - what you've done is underline what was going at the time. When Star Trek first aired - an interracial kiss on tv was perceived the exact same way as a kiss between a woman and a woman on network tv was in the 1990s. People flirted with the idea, but they never did it. The fact that the network made a huge stink about Kirk kissing Uhura (again according to Nichelle Nichols) when it wasn't even a romantic kiss...explains why they would never have kissed if the aliens hadn't made them. The reason wasn't because those characters wouldn't have done it - the reason was that back then a white man did not have a romance with a black woman on network tv - it just wasn't done. We have come a long way since then - thank god.
Today, the idea of Kirk and Uhrua sleeping together isn't a big deal.
But back then it was. With any luck in ten years time, it won't be a big deal if Kirk kissed Spock, but we aren't quite there yet.