'But that's not how how genotypes and phenotypes work for recessive alleles.'
Recessive alleles aren't immune to natural selection. It's just harder to purge them because they get exposed as phenotypes less often. As they become rarer and rarer (it'll manifest as a phenotype as the square of its frequency), selection weakens. Homosexuality, however, is common enough and the fitness penalty large enough that any recessives are exposed to a lot of selection, so it should be disappearing fast, but it isn't, which raises a lot of questions of what exactly causes homosexuality.
Recessive alleles aren't immune to natural selection. It's just harder to purge them because they get exposed as phenotypes less often. As they become rarer and rarer (it'll manifest as a phenotype as the square of its frequency), selection weakens. Homosexuality, however, is common enough and the fitness penalty large enough that any recessives are exposed to a lot of selection, so it should be disappearing fast, but it isn't, which raises a lot of questions of what exactly causes homosexuality.