But she didn't say, "I hope she beats the fuck out of him". You're changing the words to make your point. If she had said that, it would also sound pretty vile.

Imagine she actually said the same thing in your hypothetical situation, "I hope he killed her."

That would sound much more nefarious because men actually do kill women to a disproportionate degree. So when she says I hope she kills him, everyone pretty much assumes it's hyperbole.

Your point is still taken, and it'd be better if neither sex promoted violence in any way.