i can see both sides of this one.
the 'acceptable' or 'PC' terms for minorities do change over time - be that round (for example) black / coloured, acceptable terms for people with learning disabilities or mental health issues, or re-claiming 'queer' (as a gay man of a certain age, i still have to restrain an instinctive urge to take a swing at anyone who calls me 'queer') and some people aren't quite up to date with some of it.
if someone uses a wrong word, or refers to someone as he / she by mistake once, then a polite word is not unreasonable. if they intentionally carry on after the polite word, then yes they are being a twunt and deserve all they get.
but having said that, while we (in the UK) haven't quite yet reached the stage of mainstream politicians calling for the LBGTQ community to be 'erased' (as in
this twat in america) - i can understand trans people in particular having a bit of a short fuse. it's not paranoia if a lot of people are out to get you...