Being transgender isn’t a trend. It isn’t extreme. Calling transgender people “outgrowths” makes us sound like a cancer. Our dignity does not compromise or threaten anyone else’s dignity. We have opinions, just as everyone else has opinions, and we especially have opinions about ourselves, which is to be expected.

When Dawkins critiques Christianity, that is “punching up.” Christianity is a dominant cultural force in the UK where he lives and in many other countries.

When Dawkins repeats toxic rhetoric against transgender people, that is “punching down.” Transgender people generally make up less than 1% of any population, have to exist in the face of avalanches of legislation designed to make their daily existence difficult, hear toxic and false rhetoric about themselves, and are targets of violence.

This really shouldn't have to be explained: the difference between punching up at dominant powerful cultural forces and punching down at the people who have the least.

The centuries-old “more orthodox beliefs” about gender to which you refer very likely have been a product of organized religion, no? They’re not scientific; they come from Christian morality. And wherever they originally came from, they are enforced by Christians today, so when Dawkins attacks transgender people, he is colluding with Christian political forces against a shared target.