Why we don't like thinking about sex and gender
This will affect heterosexuals. Given that one can be trans simply by public declaration, Should a straight man be ostracized for refusing to have sex with a trans man who only has made a public declaration of being trans? ETC.
And, given that most of the world is NOT trans/gay/lesbian friendly, What will happen if that unfriendly world begins to question why it should turn over millennia old moral strictures for people whose life debunks those strictures, when by those people's own admission, those lives can be put on and off, almost like clothing?
I'm not sure I agree with the interpretation of Nancy Kelley's reply.
I think the interpretation doesn't give due weight to the words "entire groups". In fact you outright says Kelley criticises refusing to sleep with a "trans woman with a male body". But Kelley didn't say that. She said it's wrong to write off an entire group
The most charitable reading of Kelley's statement is something like "it's fine to reject someone with a male body, but if you reject every transperson because they are trans then it's wrong"
For example. Under that reading Kelly is saying if you reject someone who looks like Blaire White (https://youtube.com/channel/UCDmCBKaKOtOrEqgsL4-3C8Q) because they are transgender then you need to examine yourself for prejudices. I think you should assume the most charitable reading - unless you can point to further statements that suggest a less charitable one is true - and reply to that.
There's much you could say to the charitable reading. You could say that the statement that it's wrong to write off entire groups is itself a bad statement and violates the established principle that "no means no, end of story": Some people like blond hair, others like brunette hair. Some people like white skin, others like brown skin, and nobody has a right to pressure them to change.
You could argue against it for the same reason that people argue against "all lives matter". All lives do matter but if you're saying it to rebut a protest after the death of Gorge Floyd that raises questions. If you're saying writing off all transsexual partners is bad in response to an article about people feeling pressured to have sex that too raises questions.
But it needs to start from the charitable reading IMO.
I'm in a nightclub. And I get chatted up by a man in female clothing and make-up etc. He has a beard and cheekbones with right angles. He wants to have sex with me. I refuse because I like girls (biological ones) and don't want his penis up my arse. Therefore, I am a transphobe. That is a hate crime. I go to jail. Britain in...when? 2030? 2040? Can we really, in a sane society, be interpreting something as critical to human free will as choice of sexual partners as a phobia??!!
I wish it were the case that my brain could make a better stab of what nuance exists on this issue, but it's very hard not to look at it even in general terms and not conclude that it is compelling evidence for some weird societal malady. Though it is striking how many of the real trans headbangers are ALWAYS biological males behaving in a extremely destructively and sexually aggressive Alpha kind of way. I'm sure they thoroughly embarrass the thoughtful and moderate amongst trans folks who don't expect society to believe lies and surrender to bullying.
In matters of your personal sexual preference*, ought there be protected groups?
*distinguishing from conduct