bc the LI’s pronouns are used so frequently it would require separate variants for thousands of lines to match proper verb conjugations (for NB!MC by comparison, it would be more in the dozens)
That’s not how the coding works so it’s not that time consuming. It’s not that they took every line referring to MC and wrote 2-3 versions, they already established a system that changes the word based on the needed conjugation.
The way it works is that they “tag” (at least that’s my easily consumable word for it) words that need to be changed based on the LI’s/MC’s gender. For binary, it was easy, like {he} (as they tag it usually, the brackets show it’s changeable) will be ‘he’ or ‘she’. And if you see (usually a masculine) pronoun that didn’t change, it’s because they forgot to tag the word. Another common mistake is them saying his/her instead of his/hers because they tagged it as a {his} (his/her) instead of a {hisp} (p meaning possessive which changes into his/hers).
(IMHO it’d be infinitely easier if they just always used they/them/their/theirs even for binary characters because that leaves no questions and is even possibly less jarring if they forget to tag it... but PB just has to be cisnormative. Or more like, I think, they write the original script with m!LI in mind and just tag the words later... ANYWAY.)
For non-binary (MC for now), they have these suffixes coded (’y’ in the example means ‘you’) that will change any word they apply it to:
{y.s} (e.g. work{y.s} -> work/works)
{y.es} (e.g. do{y.es} -> do/does)
{y.ies} (e.g. cr{y.ies} -> cry/cries)
{y.is_'s} (when it’s she’s/he’s/they’re instead of she/he is or they are)
{y.has_'s} (when it’s she’s/he’s/they’ve instead of she/he has or they have)
If they did end up adding it, though, that would be super neat, and I’d be extremely interested in seeing how they handled it from a technical angle. Because I can’t really think of an efficient way to do it myself.
So that’s the answer to your inquiry. (I hope the way I explained makes sense and the exact examples from the coding don’t confuse people.)
And I recognize that even with the established coding it definitely takes effort to tag all the words for a non-binary LI. But if only they just wrote them as enby it’d be easier... Or, hear me out, use AI for good (e.g. proofreading the script) instead of stealing art cough sl cough, just a thought...