It is a suboptimal choice, but it's due to a lack of creativity.
Until recently we had few examples of prominent evil women - the occasional Leona Helmsley was the exception.
Now we have more than we can choose from, and the language hasn't caught up yet.
The plurality seem to be Fascist Barbies - young, attractive, extremely angry women who are paid far-right-wing liars on TV.
But then there are a whole spectrum of evil women - ones like Barrett who rely on evil interpretations of Christianity to do damage, and ones like Powell, who just seem to enjoy hurting others for its own sake.
In the case of Sidney Powell, there's the additional point that the name leads people to possibly expect a man, so the lazy joke naturally appears.
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Giuliani, Powell, Barrett and of course Trump are the natural enemies of compassionate, moral and ethical people, so I frankly don't give a flying fuck what horrible names these criminals get called.
I'm not going to judge some decent human being who is driven to anger by seeing hundreds of thousands of needless American deaths while despicable subhuman gloating scum like Sidney Powell tell a pack of obvious lies in order to try to steal an election, with the effect of killing even more Americans horribly.
Many people are damaging themselves by internalizing all this justifiable rage, and if they release some of it by calling these truly morally ugly monsters names like "Coronawhore" or "Trump's suppository", then more power to them.