Persons with CAIS have male sex chromosomes but because they are completely insensitive to androgens develop a female phenotype and are typically raised as girls and regarded as women. I disagree that it's "unethical" to determine the sex of individuals with CAIS. They need health care just like everyone else does, which means diagnosing their condition and providing them with counseling and sometimes medical interventions too. Most people with CAIS learn of their condition in their teens when they reach 15 or 16 without ever having a period. Amenorrhea at that age is a serious issue that requires medical investigation.

Since many sex differences are the result of chromosomal sex, not gonadal or hormonal sex, and exist at the cellular level and affect various organs and body systems, the fact that persons with CAIS are XY needs to be taken into account when assessing their health and their health risks, and determining which treatments are most appropriate for them.

For example, there are considerable differences between the two sexes in such areas as kidney function, how the respiratory system works, and in immune function and overall level of immunity. Whilst XX people get more kidney disease than XY people do, XY people are more likely to die of kidney disease and at an earlier age. Certain diseases involving the lungs have very different trajectories, and life expectancies, in the two sexes. XX people have more robust immune function than XY people, which means we have a much higher rate of auto-immune conditions - and we have much stronger reactions to vaccinations and suffer more adverse reactions. Similarly, the risk of dying or needing ICU care due to COVID-19 is far greater for XY people than XX people, and the sex differences grow with age - to the point where a in the age group 85+, patients with only one X chromosome are 3.17 times more likely to die of COVID than patients with two Xes.

All that said, I think that persons with CAIS have every right to their privacy and to keep their condition between themselves and their family and HCPS, the only exceptions being in competitive sport where they might have an advantage - and of course in intimate relationships. When they date, the issue of their sex and medical condition is certainly relevant, especially as most people in the population want to have biological children but people with CAIS cannot. As with any other kind of condition that causes infertility, thorny issues of when during dating the fact of infertility should be divulged - and in the era of dating apps, these issues might well be thornier today than ever in the past.

But how to negotiate matters around disclosure during dathing is for individuals with CAIS to decide, based on their own ethics and with help from family, counselors, clergy to advise them. I don't think any of them should be seen as under any obligation to make their highly unusual medical condition part of their public profiles on dating sites. The question of

Which sex are they and how do we know?

Seems germane only to someone they personally know & might want to pursue an intimate relationship with. And for sports governing bodies in certain circumstances. But I think the rest of the world will get on fine without asking those questions or knowing the answers of individuals who have this vanishingly rare medical condition.