- grouping by the way someone looks (influenced by hormones)
- grouping by reproduction capability (can or can not be pregnant)
- grouping by reproduction hardware
- grouping by which group of partners one finds sexually interesting
- grouping by various other aspects of biology (chromosomes and all)
Different areas in life really want to categorize by a different set of those aspects, and bundling it all under one word starts to become problematic. My programmer intuition tells me we need to become more explicit about which aspect we mean at any given moment.
Also there seem to be other factors which aren't understood yet:
The researchers identified a region of the hypothalamus, known as the bed nucleus of the stria terminalis (BSTc), as being responsible for sexual behaviour. This area is always larger in men than women. However, in their study of six MTF GID sufferers, a female‐sized BSTc was present in all subjects. Additionally, the size of the BSTc was not influenced by taking sex hormones in adulthood. This implies that these individuals had a powerful biological force compelling them to be female, rather than just a psychological conviction.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2600127/
But.. I guess yelling "SJW" is much easier, or something.
Chromosomes are the arbitrator of sex. We know about intersex people and have known about them for some time. None of this means men can become women and women can become men
The OP posted "*he" as a "correction" for a "she" talking about Chelsea Manning, and seems to have been offended they got downvoted.
Apparently they may not be familiar with the difficulty of assigning gender. The least politically charged way to seeing this is to look at Olympic sports, and https://www.buzzfeed.com/azeenghorayshi/sex-testing-olympian... is a good overview.
I'd draw particular attention to the case of Ewa Klobukowska who was stripped of an Olympic Gold medal for "failing a chromosome test" (ie, exactly what the OP is claiming should be the arbitrator of gender).
https://en.wikipedia.org/wiki/Maria_Jos%C3%A9_Mart%C3%ADnez-... is another case.
Ewa Klobukowska later had a son, and had her medals returned.