Well, .bi domains can already be registered, it's a valid ccTLD.
The difference is that .BI was intended for a country, Burundi. It's a proper ccTLD. It's not about sexual preference (or lack there of depending which way you look at it...)
I'm not against it in the slightest, because it opens up some very lucrative marketing possibilities... But from an end user / general public perspective I think it's kind of pointless, and in some ways more offensive than .XXX (which at least has the point of ensuring porno is easily identifiable and segregated).
.GAY would be a community TLD at best, vanity at worst.
And let's face it, it's unlikely to be particularly cohesive because of internal politik and fragmentation within the gay, or less specifically, glbt community. Some people aren't gay enough, some people are too gay because they are the epitome of a stereotype, and some aren't gay at all because they're i]just[/i] transvestites, or they're gender mismatched and will be hetero after reassignment surgery, or insist on being "lesbians" (I just assumed that was a gay woman, but feminazis tell me I'm wrong).
Same reason why you can't really do .black.
You're going to get people taking offence because they're "African Americans", not "black" (sorry, what about the non-African black people that aren't American citizens, like the Jamaicans in London?)
And what of vernacular usage of language?
People looking for "bears" are going to get a bit of a surprise when they open up bears.gay.
Again, politics aside, I think that the full ramifications of running a TLD have been thought through in this instance.
The word
gay provides another form of segregation: I'm old enough to remember when it meant feeling merry and happy, as in
having a gay old time.
Would this be the same age bracket that assumed people who were "going to camp" where having it off with other blokes?