You’re motte-baileying to ‘related to free speech’. By the standard you are setting, any curriculum-setting is free speech related, so clearly not an impermissible state action.

Curriculum-setting neither limits anyones free speech nor does it restrict their access to the free speech of others. Teachers are generally allowed to expand on the curriculum and students are given access to literature with information beyond that in the curriculum. These laws do effectively restrict access to information and ideas.