I don't "tolerate" WoT, video games or ice cream; I enthusiastically enjoy them. I tolerate illness, bad weather and waking up minutes before my alarm because they're facts of life and I can either accept them as such, live in a world of denial or be constantly frustrated an miserable. The whole basis of tolerance is allowing things you don't condone rather than aggressively lashing out at them.

That said, and my own feelings aside, while the kids would be within their rights on a street corner, that's not where they were. Ignoring the fact you can't just walk down the halls of a public school proselytizing, various schools have a whole host of dress code standards that are perfectly legal, such as minimum lengths on shorts and skirts, prohibition of professional athletic attire and in some cases required uniforms. So long as the standard is applied equally, without discrimination, why shouldn't they be able to prohibit clothing explicitly attacking religion or a religion?