Earlier quoted context omitted.
No - please do not use "it" as a catch-all pronoun for an unknown person. "It" is generally a dehumanizing term for a transgender person - though a minority use it as a pronoun (in those cases, go for it).
I’m not asking if they’re interchangeable. Just if “it” differs from “they” in some way in the above context where it sounds like that’s the individual’s preferred pronoun? Yes, calling someone “it” has been a ridiculously offensive thing to do in my life experience.
Edit: I suspect the answer differs from person to person.