The same week his state outlawed racial discrimination based on hairstyles, a Black high school student in Texas was suspended because school officials said his locs violated the district’s dress code.
Darryl George, a junior at Barbers Hill High School in Mont Belvieu, received an in-school suspension after he was told his hair fell below his eyebrows and ear lobes. George, 17, wears his hair in thick twisted dreadlocks, tied on top of his head, said his mother, Darresha George.
George served the suspension last week. His mother said he plans to return to the Houston-area school Monday, wearing his dreadlocks in a ponytail, even if he is required to attend an alternative school as a result.
I would suggest that in almost all cases a unified standard would actually be guaranteed to be discriminatory, in much the same way a unified standard for how tall you're allowed to be would be. The only thing I can think of that wouldn't would be if everyone had to have their heads shaved as "the standard".
Biologically/genetically, and socially, different (protected!) groups have different hair and expectations about how that hair can be styled.
Even the "head shaved" thing, while possible with any hair no matter what the underlying biology and genetics, would be torture for a sizable number of women in a modern society.
With the right tattoos a shaved head can be more disruptive than any haircut
If there is any appearance standard, it must apply to all students in the exact same way. If girls are allowed to have hair which "falls below the eyebrows or earlobes," but boys are not, that is discrimination based on gender. If girls are allowed to wear "skirts below the knee," but boys are not, that is discrimination based on gender.
I'm in no way suggesting that girls be held to the appearance standards that boys are held to; rather, boys should be held to the appearance standards that girls are held to.