An example of why 'cis' is harmful:
https://twitter.com/antidamage/status/1674223962614792193?t=JrsI8NIPDTzewm7XkWDL2w&s=19
One of the privileges cis women hold is the ability to get away with molesting children. They're frequently cheered on for it. Most cis women find this privilege repellent but a few like Greer and most gender critics do not.
'Cis' women e.g. women are 'privileged' and even 'cheered on' for molesting children.
This is where cis becomes hateful speech, and females are positioned as a reviled subgroup of women.