This is abysmally wrong.
Physicians don't suddenly stop needing know one's biological sex by virtue of reassignment surgery - if anything it's even more important. The mere virtue of having to constantly inject hormones to alter expression to a limited degree evidences what sex is in play. Some medication may react differently owing to sex, not just ratio of testosterone and estrogen.
You're reducing sex to something it isn't. I'm not sure to what end, because it helps no one.
> Is a man without their sexual organs still a man?
Yep.
> Well how do you tell?
A rudimentary exam could do it.
> the driving characteristics that determines sex in the medical community is the phenotypes/physical expression.
In terms of cursory glances only. In terms of actual examination, no. Absolutely not.
> The significant majority of sex related differences from a medical perspective are almost entirely hormone driven.
Entirely wrong.
> Hell there are even a statistically significant number of people who don't have the same karyotype in all their cells. See 46,XY/45,X0 mosaicism and 46,XX/46,XY mosaicism.
These aberrations exist but are incredibly uncommon. I think I'd read of a single woman thus far with XY chromosomes.
> what is left to differentiate them
What do you think is driving the need for constant hormone replacement?
Stop conflating sex and gender. Seriously, the fact that biological sex is a thing does not jeopardize gender expression and flexibility.