In any case, drawing attention to someone's homosexuality is considered extremely bad form among the Caldari. Whether you're calling them out, or they're running around being flamboyant... that's probably what got The Rabbit kicked out of the Caldari Navy - being flamboyant. He clearly says he REVEALED he was gay, and thus was discharged.
He may not have been discharged because he was gay. He may have been discharged because he started putting rainbows and pink ribbons on his uniform. This is an exaggeration of course, but who's to say The Rabbit wasn't doing something that is considered such bad form and insubordinate that they simply couldn't allow him to make the Navy look bad? Who's to say he wasn't sexually harassing other men, or otherwise being inappropriate about his sexuality? Sometimes people just like to rock the boat, and more often than not, doing that in the State can get you in a lot of trouble. It's worth keeping that in mind when you talk about someone who ended up starting an entire pirate organization.
My point is that we shouldn't assume that passage states being gay is a bad thing. We should assume that REVEALING you're gay while serving in the extremely rigid military is a bad thing.
First, I want to clarify -
Kaikka Peunato (the Guristas officer who was kicked out of the Caldari Navy) is not the Rabbit. I believe it's been hinted at in a couple places that The Rabbit (Korako Kosakami) and Fatal (Jirai Laitanen)
may have been gay if not just incredibly close BFFs, but I've yet to see it stated anywhere as explicitly as in Kaikka's showinfo. (Verone would probably know in more detail, what with his massive hardon for Guristas stuff.)
As far as the State goes, the population issue seems like the most likely reason for a taboo on public homosexuality. Most PF I've read over the years has given off a vibe of "DO YOUR DUTY FOR THE STATE, CITIZEN" at varying levels of intensity; the notion that having one or more children through various means would constitute one of these duties seems reasonable.
I would also point out that in a society where efficiency is a prized trait - literally to the point where "who gives a fuck what it looks like as long as it does its job" seems to be the prevailing attitude among ship designers; just
look at the Blackbird and Moa hulls - that even if methods of procreation for same-sex couples are available, they would be regarded as less efficient and not as cost-effective as normal intercourse: it's cheaper to provide incentives for heterosexual procreation than it would be to provide for same-sex couples.
I could also see something similar for the Republic for similar reasons, but then, I don't really dig too deep into Matari RP to have a good enough grasp on that.
For the Gallente, I'm assuming that the average policy is "nobody gives a fuck, do what you want with whoever you want as long as you're not breaking any laws."
The Amarr are where it seems to be a little more tricky. I expect a more widespread "don't ask don't tell" policy on most personal subjects; that is, nobody cares -that- much about who you sleep with or what your kinks are as long as you keep it behind closed doors and out of the public eye -
and as long as it's not something illegal.