idk if it was an accident or on purpose but i appreciated it
It's because pronouns in Japanese are not gendered. Pronouns and adjectives for people in Japanese are mostly, if not all genderless (unless purposefully gendered).
That's why in yaois (because I'm a fujoshi) hiding the fact that they are in a same sex relationship is easy when simply using pronouns. Their pronouns ARE saying "they" but people assume the gender. Even the word "koibito" meaning "lover" is genderless. And this is also why many misunderstandings in shoujo and/or gender benders begin with characters' names because not only can names be unisex but so are pronouns.
And so as Aoi's gender had not been revealed, they/them pronouns are the only option. In fact, it is more accurate. However, I agree that I appreciate them.
dang