From another article, same author, which names some of the groups:
These guidelines were presented to America as drafted by "thirty-five religious groups." The truth is they were drafted by the American Muslim Council, American Humanist Association, Americans United for Seperation (sic) of Church and State, many more recognizable secularist groups among a few Christian-sounding names, along with the ACLU which also holds the copyright.
Bush Country
I have no brief pro or con on the guidelines, but if you Google "guidelines on Religious expression in public schools", you will find them posted on the web sites of the Christian Legal Association, American Center for Law and Justice and Focus on the Family, either neutrally or favorably. As I remember the coverage at the time, these particular guidelines in fact supported individual student expression, as against teachers who wanted to confiscate Bibles, etc.
I'd recommend reading the full guidelines and deciding for yourself.
http://www.aclj.org/ussc/add_info/doe_religious_expression.asp