She has the explicit First Amendment right of petition for redress of grievances. She will get a lawyer and sue the hell out of them and win.
I hope she does. The district will use the defense that her actions negatively affected her ability to do her job. However, since her issue was just as much political as it was personal, she would have a very strong case. School districts have no restraint when it comes to trampling on employees and parents rights. After all, they get to fund their defense with taxpayer money! If enough taxpayers put enough heat on school districts, this nonsense would stop.