I think that there's a difference between the kind of play with gender that science fiction as a genre allows (since there's no reason aliens should have a fixed gender, or any gender at all (in the sense we mean), or thatthey should have only two options), and the kind of play with gender stereotypes that can be sound in relationships like Lee/Kara. Because yeah, there are many people who don't fit into traditional het stereotypes for one reason or another, but I think that to describe all these people as "queer" actually weakens a rather useful term.