Choice of personal pronouns

Elliot Page posted a statement on Twitter introducing himself as transgender. He told us his name and pronouns (he/they).

What exactly does that choice me? They are both nominative pronouns, one singular and one plural. When would I use “they” when referring to Elliot Page? I don’t mean this to be just about Mr. Page, but in general, aren’t usually a nominative, accusative, and possessive pronoun given?

Page’s designation of “he/they” are both singular pronouns, but the difference is one is singular gender-specific and one is singular gender-neutral. Similar to how “you” can be both singular and plural, “they” is being used that same way. English doesn’t have a widely used gender-neutral single personal pronoun, so it’s not unusual that you take it as being plural. But here it’s being used as a singular pronoun because it has some history of being used as a singular, gender-neutral pronoun. So in this sentence:

The “They”(1) refers to all the actors. The “Their”(2) refers to Page as a singular, non-gender neutral pronoun.

I know about the singular they. But it’s used when the gender is unknown. Why wouldn’t I say “his portrayal…” Using ‘they’ would indicate there is gender ambiguity, something I’d think he’d not want at all.

I didn’t see any reference to pronouns in that link.

Given that there is a very extensive discussion of the meaning of gender pronouns in reference to non-binary individuals in both the thread on Page in Cafe Society, and in ATMB, I am going to close this and refer the OP to those threads.