To do my usual thing of stating what should be bleeding obvious to everyone:

If we are to boycott/ban/reject anything and everything whose creator has ever done/said/ thought anything which is at variance with modern, liberal, enlightened ideas, then we are all going to be running around naked in the forest, carrying sticks and stones and grunting at each other. Because everything - every single thing - that we have has been made, or altered from its natural state, by methods and techniques developed by people who. by modern standards, were horrible people.

Our most basic tools - flint blades - the foundations of engineering - the wheel - were not invented by thoughtful and considerate people, but by desperate and brutal primitives always one bad day away from extinction. The long process of civilisation, of developing our technology to the point where we can allow otrselves to even have sensibilities, let alone our modern ones, means that almost all that tehcnology, plus the art, poetry and writing, that forms said civilisation, originated in the minds of sexist, racist, homophobic bigots. Our ancestors were not transphobic, true, but only because the idea of anyone being transexual would have been unthinkable for most of them. And before anyone says anything, the same is true of all cultures!

J K Rowling is an idiot, I'm not arguing with that, but nothing she's ever written or is ever likely to write or say has caused a fraction of the harm caused by Mein Kampf, Das Kapital, the Bible, the Qu'ran or anything written by Ayn Rand! Rich she may be, but an intellectual heavyweight she is not. Her transphobia may have its roots in her personal experience and a deep-seated fear of male abuse, or it may just be stupid bigotry. I don't know and I don't care, and neither should anyone else. There are far more important things to argue and fight about than silly games and silly films made from silly books written by a silly person!