Queer Cosette, You're Such A Lonely Child

Gay Cis drama student, She/Her pronouns, with an interest in French Lit, sci-fi, tea and knitting.

You have a fair point, but given the fact that Ystin calls zirself ‘Sir’, refers to zirself as a man on several occasions in the series, I think it would have been simple enough to use male pronouns rather than misgendering Ystin altogether.
Venditti seems to be under the misapprehension that this run of Demon Knights is Grant Morrison’s Seven Soldiers, where Ystin was literally a girl in disguise. That’s clearly not the case in Demon Knights, which shows a disrespect for the character and the previous writers.