I worked in SF from 1993 to 1999, and the office I was in had quite a few gays and lesbians who had moved there from other parts of the country because it was SF. So although SF is certainly majority straight, it definitely has a pull for people who don't want to worry about homophobia every day of their lives.
I don't think it's a slur to say Utah (or Idaho) is largely conservative, or that SF has lots of GLB's. Voting patterns alone confirm that, and I have both religious conservative friends and gay/lesbian friends I'm very fond of.
Obviously this is a "homeland" that requires constant immigration (though there are plenty of GLB's raising kids, the ones I know are very responsible parents), but as long as there are folks who can't handle sexual differences, or whose imaginary Friend tells them gays are evil, that's not an obstacle.
Ironic footnote: several of the transplants to SF did so well they were promoted-- and transferred to supervisory jobs in Jacksonville, Chicago and Dallas!