FYI, There are other languages such as spoken Chinese whose pronouns are the exact same for he/she. So, not all languages have such a delineation.
You left out a couple.
she/her/her/hers
they/them/their/theirs
And, of course:
he/him/his/his
I was only referring to why someone might use “she/them”
I find it awkward as well, but as I understand it: using the plural form is common in British English when referring to a company. For example, “Apple are releasing a new iPad next month”. So to make it easier for my poor brain, I sometimes visualise the person as a collection of biological cells. Makes it easier to say something like “that belongs to George; please give it back to them”.
Ok, consensus is it means either the gendered or the nongendered pronoun is fine for both object and subject.
That makes a lot more sense than what I was imagining. Ignorance fought.