Getting a bit political here but I don't think JK Rowling is being particularly honest there or at least she's lying by ommision since American's like Jim don't seem to get she's the old kind of feminist who goes on about the patriarchy and it's likely the real reason she's upset is that trans women are increasingly being legally treated as women in regards to things like short lists/positive discrimination, being admitted in womens shelters and that kind of thing.
Jail is a big issue, not for the obvious reason but because of things
like this where many feminists like her want to abolish jail sentences for women with the theory that basically women are only ever criminals because they're victims of ciricumstance, unlike men, and if men can legally identify as women it completly ruins that idea, similarly with other things
like the current campaign to make being percieved as misogynist a hate crime.
Basically JK is upset troons are treated legally as women or even with preferential treatment to women in the modern woke world since there's a zero sum competition for limited resources between troons and women (She being one source with her charities) and if they didn't I'm sure she'd be happy to virtue signal about troons all day long.
But anyway those two groups fighting never ceases to be amusing!