She knows she is doing it and doesnt care.

Like every conservative, they just want queer people dead, unless its their own children.

She’s not a conservative, she’s a liberal (in the political science sense of the word, not the USian synonym for leftist).

It’s not 100% clear where Rowling’s transphobia comes from. She certainly fits into the group of transphobic cis women who have been abused by cis men and concluded that all men are evil, including the ones that want to be women.

But there’s also a dynamic which I think you can see with Graham Linehan and Dave Chappelle as well. Born into comfortable middle-class families, well-educated, never really thought about their bog-standard liberalism. Became extremely successful, became accustomed to near universal adoration, made a thougtless transphobic comment/skit, received criticism and reacted with absolute fury at the idea they could possibly be prejudiced about anyone. Because they’re liberals, you see.

All three just keep digging that hole deeper rather than face up to the idea that maybe they got something wrong. Linehan’s career is over (as is his marriage), Dave Chappelle is hanging on by a thread and flirting with the right, and Rowling doesn’t give a shit because she’s a billionaire and does not have to give a shit about anything at all.

and Rowling doesn’t give a shit

Basically when a virtue-signaling crowd wants you to confess your sins or something, not giving a shit is the right response. One can make it even better if in possession of a machine gun, of course.