Looks like we have a latter-day version of the BYU ban on beards. How people wear their hair seems to me a form of expression. Even more it is a form of expressing one's identity. In the case of minors, it should be left to them and their parents.
https://www.washingtonpost.com/nation/2021/10/21/texas-students-long-hair-lawsuit/
School officials in Texas forced a 9-year-old boy to serve an in-school suspension for a month, deprived him of recess and normal lunch breaks, and banished him from campus to an alternative school — all to pressure the fourth-grader into getting a haircut, a new lawsuit says.
Still, the boy refused to obey what he believes is an unjust school policy that bans boys from having long hair.
The boy, identified as A.C. in court documents, is one of seven students suing a Texas school district for what they call a discriminatory policy that requires boys to wear short hair. The American Civil Liberties Union of Texas filed the federal lawsuit Thursday on the students’ behalf against the Magnolia Independent School District, which serves some 13,000 students about 40 miles northwest of Houston.
The students, aged 7 to 17, allege that the district’s policy prohibiting boys from wearing long hair is based on gender stereotypes that violate the Constitution. They say administrators apply it unevenly, allowing some boys to wear long hair that violates the district’s grooming standards while punishing others. Those suing the district said that punishment has caused them “immense and irreparable harm.”
the "immense and irreparable harm" part is hyperbole, albeit mild hyperbole by today's standards...but this strikes me as a significant case for those of us who care about freedom of expression...and i might add this is not a private company deciding what kind of activities to permit on its platform...or a private university banning beards...this is government infringing on citizens' freedom of expression