I've done some thinking about this. Just because it's labeled as "Gay Only" does that mean that straight men or women who enjoy going on holiday with gay men and women are excluded based on their stated preference of being hetero?
If not then it would appear nondiscriminating.
How does one certify their gayness? What keeps a person from lying about their sexual preference and stating after the holiday that they found no one of their same sex appealing.
In the lat 70s early 80s me and my friends tended to go only to gay 'nightclubs'. Less agro (dangrous times). Only about third of our group were gay. We got a certain amount of grief at the door, but were always let in. Nay bother.