http://www.nbc.com/saturday-night-live/video/sexy-cakes/n10536

Perhaps he meant a main character who was either gay or lesbian as their primary or exclusive orientation?

I suspect the reality of the Star Fleet culture at large leaned closer to “nobody cares, preferences differ” than no gays or lesbians – at least, by the time of DS9.

Looking behind the curtain, Star Trek’s creator has been quoted discussing his homophobia, and the struggles he had overcoming it to any degree. Rumor has it, he planned to include at least one LGBT individual in Next Gen, but when he passed, creative control passed to Rick Berman, who (according to various sources) prevented that from occurring – whether from his own views or his beliefs as to what the studio and TV audience would allow is unclear. Ronald Moore says they simply failed at portraying LGBT individuals, and hints that the studio was sensitive even to seeing crew members in the background holding hands, etc in a way that might suggest their sexuality.

Complicated issue, and in part, a reflection of the times and the medium.