Regarding my Facebook grammar post, Montoya said:
No dummy, this means that Hernan has not chosen a gender on his/her profile, so Facebook has to use the gender-neutral “their.”
“Their” is gender-neutral, but it’s plural only. English has no gender-neutral singular version - only “his”, “her”, or “its”.
Technically, “his or her” works, but it’s awkward. Preferably, the sentence is reworded to avoid the need for this linguistic oddity when the noun has a gender (so “its” is wrong) but the gender is unknown.