I don't think transgender identify as in between the two. I believe they identify as one gender or the other. This is their biggest complaint when it comes to bathrooms. They don't want a third bathroom as if they aren't real men or real women, they want to be let into the bathroom of their choosing.
Why do transgenders have to be their own special unit? Why they can't they also fit into the male or female categories? I'm not getting why some people have to be special snowflakes. Last time I checked transgender people are born one gender and then want to be the other. There's not some illusive third gender that is hiding in the shadows.
Saw a similar question a while ago. I totally agree the whole gender binary is complacently incorrect a "purple" option or something would be nice for people who don't identify as male or female. I just don't think there is enough demand for it so it is not likely to be a feature they add anytime soon.
The site reflects society to a degree so if it became mainstream to have a third sex in outside society then site may adapt. My own personal view is that if user lives their life as a woman they are entitled to use pink profile.
The third sex i guess, they offer their own unique perspective.
The incidence of transgender has not been determined in any authoritative way and it is dependent on the definition of transgender, but most studies in Western cultures estimate the incidence between 1/7,400 and 1/104,000. Why should this website be geared towards a group which has such a low population count and which has other web sites specifically aimed at it?