'Cis' is a Latin prefix and 'cisgender' is a term used legally and scientifically as a descriptor for anyone who identifies as the gender assigned to them at birth.
I was assigned female at birth and I identify as a woman, so I will refer to myself as cis no matter how TERFs try to frame it.
Beyond that though, the way JKR's current avatar screams "comic book villain" is some other level of unintentional self-parody.