It's a Star Trek trivia factoid. It was on one of the many documentaries about the making and history of 'Star Trek', Shatner, and Nimoy. I do not remember which one.
I am sort of a Trekker and have watched them all. Also, word goes, that interracial kiss did not help either. It upset a lot of people at the time, both Black and White.
The show was ahead of its time.