Banning ID or creationism on religious grounds is restricting the free exercise of religion and so should be unConstitutional.
Even if one wants to say it's mixing religion with science, that's a guaranteed freedom under the Constitution. The way secularists have interpreted the first amendment has turned it upside down. Separation of Church and State is not separation of religion from science, philosophy or any other thing. It's just the idea the State cannot rule on religious matters.
In fact, by intruding into education, the State has violated the first amendment by insisting education be separate from religion and so once again, banning the free exercise of religion which is a guaranteed right under the first amendment.
The State has no business telling religion what it can and cannot do and teach with respect to children; nor restrict religious ideas from education if a local community wants to include those ideas.
What local communities cannot do is force people to adopt a religion but religious ideas per se are guaranteed equal status in the public square if one reads the Constitution correctly.