Anyone who says ‘they’ cannot be singular can fight me. And also a whole lot of genderqueer and nonbinary people, and a whole lot of binary trans people who aren’t down for hurting their nonbinary friends, and a whole lot of cis people who aren’t down for hurting their trans friends. We will also throw down over neopronouns such as ey/em, ze/zir, and so forth.
They can also fight a whole lot of other people, starting with Will Shakespeare:
Arise; one knocks […] Hark, how they knock! Who’s there?
That’s Romeo and Juliet and Shakespeare isn’t even the earliest English writer to use singular ‘they’. Just a famous one.
Further, contrary to popular belief, pronouns are not gender-specific. Typically ‘she’ is the correct pronoun set for a drag queen when in drag, ‘he’ when not, for example; there are also cis lesbians who use ‘he’. The correct pronoun set is often tangled in with gender euphoria and gender dysphoria, and deliberately using the wrong set is almost always in order to misgender the pronoun referent (which is cool if it’s in service of helping keep a closeted trans person closeted at their request, but not otherwise). But that doesn’t mean the pronouns themselves are gendered, any more than slacks or skirts are; it is all very messy and complicated. Sometimes I wonder if things would be easier for monolingual English speakers if English had grammatical gender outside singular third-person pronouns, because about half of los búhos are female owls and about half of las palomas are male doves, and the vast majority of Mädchens are girls or young women, not agender, neutrois, or otherwise nonbinary or genderqueer people.
\braces for all the Spanish- and/or German-speaking trans people to explain at length how wrong they are\
And because I know people† have said this thing (though I trust no one reading this would), ‘it’ for people who use pronouns other than ‘he’ if the doctor at their birth said they’re male or ‘she’ if etc female is flatly unacceptable and also utterly horrifying, with the sole exception of when used for people who have explicitly stated their correct pronoun set is in fact ‘it’.
Anyone who says that can fight a whole lot of feminists, too, whether the said feminists are trans-affirming or not.
I’ve seen both ‘themselves’ and ‘themself’ in the singular. I prefer the latter, reserving the former for plural instances, as with ‘yourself’ and ‘yourselves’.
† my mother. my mother said this thing. not to me but after I told her my pronouns aren’t what she thought they were.