If an employer specifies distinct garments for males and for females, and if a “male” employee wears a garment classified for the opposite gender, then by definition that male is due to be construed as a member of the other gender. The dress code thus self-proves the validity of his attire. In other words, if a company’s definition of “male” is someone who who only wears pants to the office, then the person who also wears skirts to the office must not be “male” according to that dress code or else he wouldn’t wear a skirt. So if the dress code establishes that he is not “male” then the dress code self-proves that he is permitted to wear a skirt because “males” do not wear skirts and thus if he is not “male” according to the dress code, then a skirt is appropriate. I would imagine that skirt-wearing males would not care where they land on the dress codes definitions of male because if such men cared about external opinion….well, they wouldn’t wear skirts at all. On the other hand, the skirted male might be happy to lay claim to a “gender non-conforming” label and with that it is appropriate that he mix-and-mingle his wardrobe. More bluntly, a gendered dress constructs a gender dichotomy where males are expected wear “masculine” garments and where skirts, dresses, and sandals are regarded as “feminine” so one who wears such things is not “masculine” and therefore not constrained hy the presumed “masculine” dichotomy.