In zoom training sessions you get assigned to a sub group when they split you into rooms for discussion. Someone else decides where you are and off you go. That's what assigned means.
If you were assigned a sex at birth, that would mean we all came out of our mums, smooth like dolls between our legs, and a midwife went, 'this one is a girl' and a cunt appeared, or 'this was is a boy' and a penis and testicles appeared (and all the internal sex stuff too).
Even on their own terms, assigning sex does not make sense to Gender ideologists. Being trans means, according to them, a gender identity at odds with your sex. So you still have a fixed sex. So they should be comfortable with sex existing as a fixed and observable thing.
Instead its like, at some point in the early days of Gender Ideology, the conversation went:
TRA ' TW are women because of their gender identity, so they should be in all the women spaces and things.'
Feminist ' But those spaces exist to protect women because of differences in sex, not gender identity.'
TRA ' Yeah, well, well, yeah well, , yeah, well, well, er, umm, well, er, umm, yeah well, sex is not really a thing anyway! Yeah that its it! Sex is not really a thing anyway, so there!'
And after saying that, they got stuck in all this nonsense they then had to make up to defend why sex is not really a thing and doesn't really matter.