To be clear and not antagonistic for a change, I want to say that in the first place people who go on about not calling pupils in girls' schools "girls" irritate me too. For different reasons, perhaps -- they give people like Piers Morgan an excuse, it seems, to lump everyone who remotely shares the same view (that gender is, in fact, not as binary as we have assumed) in the same boat, and so ignore the reasonable in terms of the unreasonable. Put another way, Morgan et al are deliberately misrepresenting the arguments by taking extreme versions of them, because of course they are -- but many miss that.
Take "cisgender". This word doesn't do anything other than serve as a useful shorthand for "people whose gender identity corresponds with their biological sex" -- a shorthand that makes sense, because nowadays we recognise that not all people are "people whose gender identity corresponds with their biological sex". No-one's identity is threatened, or devalued, or otherwise affected by inventing or using this word. It just saves having to repeat that phrase when comparing transgender people to "not transgender". That's all.
And yet apparently some people perceive it as somehow a devaluation of their identity. I can't imagine where that comes from. Only I can, because there are -- unfortunately -- a number of people, both LGBT advocates and reactionaries -- who are determined to turn acceptance of LGBT rights into some kind of zero-sum game. "LGBT people can't get equal rights unless we take away other people's." That's not true. But Morgan et al paint a picture where it is. And, sadly, they seem to have no shortage of ammunition.
Still, I don't apologise for the "aww, shame" remark. "Cisgender" is only a shorthand, carries no offence, brings no devaluation of most people's identities, and I have no time for people determined to pretend that it is so. I'm not going, to coin a phrase, to go about "treading on eggshells".