I wrote a piece myself about this very thing, I'm glad you are pointing it out.

JKR is a fantasy author who writes about magical fictional fairy tale people have a rich universe full of contradictions and impossible magic. This in noway makes her qualified to make judgements on trans issues. She knows about as much about trans people as my grandmother. Of course she is entitled to her opinion, as well are, but that doesn't mean we need to listen to her. Writing magical fairy tales doesn't mean she has any sense or logic.