If anyone's first thought on seeing a report of a murdered woman is "but what if she was trans" then what you're actually telling the world is it's fine to kill trans women. That they don't count. That they (and their families) are fair game, have committed a terrible deception - and don't deserve respect.
That is not what this was at all. Counting dead women highlights femicide. No-one's saying it's fine to kill any man, just that that account only highlights women, because when it was started, there was a distinct lack of care about women who were murdered.
No-one is fair game. No-one should have 'gone after' any family on twitter.
The difficulty again, is that when news is persistently mis-reported, it makes people suspicious and some people go too far. If Karen had a source which gave accurate information on victim's sex, this wouldn't be a problem, but because sex and gender-identity have been muddled together, both attempting to use the same words for different concepts, that can sometimes go wrong.
Doesn't make any of the abuse coming at Karen, or that went to the families of the victim acceptable.