Much of this has already been mentioned on the thread, so this is just a personal reflection on the subject. It's clear that Fry is arguing for 'kindness' and for people to be careful in their language. That in itself is an odd position for someone who made a career out of saying outrageous, naughty, impolite things and who has himself spoken out vehemently about the chilling effects of cancel culture on free speech on which his profession as raconteur depends.
He's publicly opined on the issue multiple times over several years, including reversing himself and issuing mea-culpas. If he wants to criticize someone else by name in the press, I think it's reasonable to expect that by now he's fully familiarized himself with the the subject.
Rowling's position is coherent and clear, and hasn't changed markedly since her "dress however you please" tweet. Is Fry objecting to Rowling's 'misgendering'? Well, use of sexed pronouns has proved to be critical in debating the subject clearly. That's not Rowling being radicalized or 'not nice', it's a logical conclusion, and now an empirically observed fact. Is he objecting to her categorical position that in no instances should transwomen be allowed to access to women's spaces and services? There again that's justified by the fact that even if you believe there are instances of a sort of 'true trans', it's impossible to legally distinguish that in a way that keeps out highly objectionable, and obviously non-truetrans men. And empirically we know they will try to access those spaces in a high proportion. In addition Rowling has explained she does not accept there is a phenomena that can be called 'true trans'. To her triumphalism on the victory of a hard fought legal battle into which she has an enormous, public personal investment? One could go on.
In short, if Fry wants to wade into the debate yet again, he owes Rowling and us a clear articulation of what he supports and a proper critique of just what, exactly, is objectionably or incorrect about Rowling's statements and posts. He refuses to do that, and it's impossible not think that he's being hypocritical and cynical, and more than a little lazy, on a subject he claims to be so emotionally distraught over.