Satsu to Kennedy: Buffy sends the other lesbian slayer to check up on me, and I'm the one you're yelling at?
I've tried but I can't read this line as not saying that there are exactly two out gay slayers in Buffy's organisation. IIRC, it's been established there are thousands of Potentials who were activated in Chosen and about a third of them are working for Buffy. So at least six hundred slayers, at a rough guess. Of whom apparently all of two are both gay and out. Tedious people argue at great length about the proportion of gay people in the population, but most estimates I've seen are in whole numbers of percent, not an order of magnitude down from that, which is what we're presented with here. There should probably be a few dozen lesbian slayers, not two.
None of the possible explanations for this seeming anomaly please me that much. The plausible-but-disappointing one is that there are strong social forces among the slayers that keep the lesbians closeted. The icky one is that somehow lesbians are less likely to be supernaturally chosen by whatever force chooses slayers. (Then again the ritual with the old guys in the distant past that created the First Slayer in that episode I can't quite remember the name of did have nasty overtones so it at least fits.) And of course the let's-summon-Osiris-to-try-and-resurrect-a
(ETA: those are all "Watsonian" possible explanations of course. The "Doylist" one is that DeKnight didn't think it through. But I can't use the word "Doylist" with a straight face, it just makes me think of doyle_sb4.)