Misandry is a made-up word.
If a man uses violent language against women, even jokingly, it reminds us of the horror of violence towards women which sees two a week in this country actually die. So it's not much of a joke.
When a woman uses similar language, as the reality of female aggression comes nowhere close, we can accept it as hyperbole.
Language, and the way it is understood, has some basis in actual social experience. Which is why a thread title about wanting to hurt a child would be reviled by most people reading it. Because it actually happens.
The fact is that women do not routinely physically abuse men. So to react to verbal rantings as equivalent is splitting hairs, and missing the objective facts.
I don't especially like violent thread titles btw, but it's just silly to say "Oh it's just as bad as if men say it", because we are comparing apples and oranges.