"There are only two sexes and genre doesn't exist" is simple and wrong. "Genre is a social construct and is a spectrum" isn't.
Sorry you feel threatened by people not wanting to be pigeonholed into your tiny tidy restrictive categories.
What I think is irrelevant, what is codified as the stance of the US Government is. They are acting on that assertion.
I'm sorry you feel threatened by it and pigeonholed into your beliefs. This is the exact status of definition for the HHS and USG.
Sex: A person’s immutable biological classification as either male or female.
Female: is a person of the sex characterized by a reproductive system with the biological function of producing eggs (ova).
Male: is a person of the sex characterized by a reproductive system with the biological function of producing sperm.
Woman: an adult human female.
Girl: a minor human female.
Man: an adult human male.
Boy: a minor human male.
Mother: a female parent.
Father: a male parent.
You can argue what you want, but they are enacting actions against what they have defined as truth. That's the by product of winning an election, you get to make the changes you ran on.