LOL he just told her she'd be pretty if she smiled more. What an asshole. Being an asshole, to an asshole. There's no winner in that exchange.
I have a theory that JKR got sexually abused by a trans woman who had won and then abused her trust, and hasn't processed the trauma from it. And doesn't want to, nor feels she has to. So she just decided to hate that whole class of people instead.
I think that's far too generous. It tries to justify her hate. I think it's far more likely she's just a conservative asshole. Most anti-trans people have never even had a conversation with a trans person. Ignorance is the true source of hate, not betrayal.
Lots of people interact with trans folks on a daily basis and have no idea. I'd bet she encountered someone trans at some point in her life and had no idea.
David Attenborough voice: Here is a rare treat! We are now witnessing an encounter between narcissistic billionaires. Make no mistake, this is no courtship however; notice the pointedly cordial tone. This is a veiled insult. They see themselves, and even they feel compelled to strike.
We can distinguish an animal's self awareness by how they respond to a mirror. Do they recognise themselves, or do they perceive a threat? Billionaire specimens are usually out of budget for science departments, so we must trust in careful observation to deduct their nature.