I hope for your personal consistency that you then are also okay with a woman in a hijab creating educational videos for youtube.
As far as the crazy atheists go, there's a type of "atheists" that treat atheism as a belief system, but have neither tried nor have the intellectual capacity to come up with their own, original understanding of why there is no god. However, there is a fundamental difference: Every crazy atheist is on their own, there's no "atheist institution" that backs their craziness.
For cults (and the only practical distinction between a religion and a cult is just the amount of followers), that's not the case - you have a power hierarchy, sometimes more, sometimes less flat, that advocates their belief system.
It is therefore okay for a teacher - when asked(!) about it - to tell children about their personal beliefs. It is absolutely not okay for a teacher to tell unasked, or to tell children about the belief system / cult they are a part of.