*I* can though! JK Rowling has denied the existence of the Holocaust and routinely enabled genocidal behavior through her continuous crusade against marginalized communities, and is an active threat to a decent, caring, and overall better society.
To be fair, we *can* call her a hateful transphobic bigot, we just can't accuse her of specific things. Like i can call her a talentless hack who couldn't write a decent story if her life depended on it because that's an opinion and you can't sue for that.