Thank you, that was very interesting.
Whatever one's feelings about other aspects of trans issues, I can't understand why trans allies would find straightforward recording of biological sex, IN ADDITION to gender identity, a problem.
The census data isn't going to be accessed by colleagues, friends, family etc. to misgender a trans individual.
You can still record your preferred gender identity.
If an individual is so mentally fragile that accurately answering one brief question on a government form about their birth sex once every decade causes them significant distress (rather than passing annoyance) then that individual needs more appropriate support than the government adjusting the form to collect inaccurate data.
And, last but by no means least, trans people can BENEFIT from having their natal sex recorded accurately. Transmen and women may experience health issues specific to their birth sex or their trans status, and the NHS can allocate resources more appropriately if data can be gathered accurately. Trans people deserve adequate healthcare! That includes things related to their birth sex.