Not when Children are forced by truency laws (and their parents forced to pay) for “public facilities” including public schools, and the so called education which goes with them: the students 1st Amendment rights take precedent to some bureaucrats notion of what is correct or not. Bottom line unless these students were threating the life or propert of another student or adminstrator (teacher) then they had the perfect right to have the Confederate Battle flag on any school property (as long as the flag wasn’t endorsed by a teacher or school activity)!
It’s not such a black and white issue. As for the truancy laws, parents have a right to put their kids in private school or homeschool them, so they can avoid the public schools if they want. Also, while the schools are funded by taxpayer money, the taxpayers also get to vote for their school board members. If they don’t like the policies coming out the schools, they have the power to instill new leadership.