But it's OK to apply the ugliest slur in the language to people (unless an individual personally objects), and it's OK to overload a plural as a singular however jarring it is to the reader or listener.
There was an article on Washington Post about a person who wanted to be referred to as ”they” and half the comments were about how confusing it was.
I use "it" in reference to people like Donald Trump, Sarah Palin, and Kayliegh McEnany. Because they are too vile to deserve the usual pronouns.
And I will never in my life refer to a single person as "they." That is simply disgusting.
Go ahead, put "themself" on your CV. And wait for the phone to ring.