Realised I need to frame this comment better. Here's my second attempt:
JKR has raised such an important issue because it cuts right to the heart of how to move things forward at a societal level.
At that level, we've got far more Be Kinders than any other group in the UK i.e. the majority of the population:
a) isn't really thinking about this issue much - they see it as a fringe issue
b) believes it doesn't affect them, despite the impact it's all had on free speech and women's rights
c) isn't influenced at scale by religious thinking. Obviously at an individual level plenty of religious people don't (conflate and) judge sexual orientation and gender identity as morally wrong but there are also plenty of religious people who do. This is where the difference in the UK and US populations is likely significant: according to Google, 68% of people in the US are Christians (1% are Muslim) whereas only 46.2 of people in the UK are Christians (6.5% are Muslims)
d) don't question why LGB and T have been packaged together, so don't think about why it's important to remove the conflation
e) are aware that gay people have been unfairly treated in the past and want to be a part of putting that right
f) want to live and let live
If we're going to achieve better protection for vulnerable children and young people (the people on the left-hand side in the screenshot below) and stop the erosion of women's rights (due to the actions driven by the people on the right-hand side) it's important to recognise when to stand firm on language and when to accept that doing so causes more issues than it solves.
A good example of a sensible place to stand firm is "there's no such thing as a trans child" because a) it forcloses on the outcome of therapeutic exploration (David Bell articulates this brilliantly) b) children get specific protection from harm because they are too young to make informed decisions that impact their lives c) it recognises that children have been taught by adults that everyone has a gender identity.
Obviously all the above could be said of vulnerable adults too. Especially so because the Cass Report, the announcement of the review in to adult services and the WPATH files all demonstrate that consent isn't really informed at all because of the lack of evidence base. However, the fact remains that adults will always have autonomy to make decisions about their own bodies, even when those decisions are linked to a belief; whether that's someone who believes that we all have a gender identity (and is distressed because theirs doesn't match their sex) or any other belief.
The gender dysphoria book that Sue and Marcus Evans wrote explores this distress in young people and how to support them. They unpick the "old school transsexuals" too. They do all of it without judgement and without needing to affirm or deny anyone's belief that everyone has a gender identity.
"Old school transsexuals" include people who genuinely believe everyone has a gender identity (even if some do recognise that they haven't actually changed sex), people with internalised homophobia and those who see a convenient front to indulge their fetish. And yes, it's the pushing from the activists in this group that led to the GRA mess.
However, at a societal level it's important to recognise that we can't stop people believing that everyone has a gender identity (and that it's possible for your own to differ from your sex) any more than we can stop people believing that it's possible for a human to be the son of god, born to a mother who was still a virgin at the time. It's a waste of effort to try.
Yes, language has been mangled. But JKR is more than capable of knowing when it's important to stand firm on that and when it's sometimes more helpful to use the language of the belief to make a point. The same rings true whether you're chatting to your friend or writing tweets that millions will see e.g. to make the point that males with DSDs shouldn't be in women's sports, it might be better to use "she" when talking about Caster Semenya to your friend. Or perhaps your friend says "she" and you say "he". I've been in exactly this scenario with a relative and because I was aware that my points would likely be discarded as a kind of bigotry if I used "he" and/or insisted that my relative did too. We'd never have got past that point in the conversation. As it happens, by the end my relative had recognised that she hadn't been aware Semenya had testicles, had always just assumed people were being mean and when the penny dropped said: "Oh, so she's a man!".
There have been lots of great posts in this thread but to me, the ones that stand out hugely are from Redtoothbrush because, just like JKR, Red's posts recognise the value in pushing back on the impact of the belief being enforced on society as a truth, rather than getting lost in fighting people on the tenets of their belief. Sometimes there are greater gains to be had by using a word like "trans", even when you know it's a broad umbrella, and then articulating your points. It's the substance of the argument that matters more than the words. Sadly, we've now got a government, under weak leadership from Keir Starmer, which wants to push the belief in gender identity on to our society as a truth. Articulating why this shouldn't be allowed is far more important than policing the language of the people who are doing this well. JKR is right: when someone is as informed as she is on how to articulate this, it is indeed wearing.