The 10th Amendment is not absolute where state abridgment of constitutionally enumerated protections is a problem.
Noting that I am not familiar with referenced school district please consider the following.
Are legal majority citizens in referenced Pennsylvania school district being reasonably represented by school board? Or did conservative voters, if any, possibly get lazy and stay home on election day?
I’m not sure where in the Constitution, the Bill of Rights, or the various writings of the Founders where bathroom / locker room assignments are discussed.
Since you are obviously an expert on it, could you please elucidate me on where/ why this would be in the USSC’s jurisdiction? Thank you.