People will sue over anything. Should the classroom have went as far as they did? Maybe not. Maybe it could have simply have been explained to the students without an actual demonstration.

Teaching children about the culture of others, in my opinion, is okay BUT when religious beliefs are entwined into culture and then placed into a ceremonial sense/event, etc, that IS going way beyond merely educating the children.
The minds of children are extremely susceptible and pliant hence they CAN be easily worked on and eventually controlled,etc, which may not always be a good thing, for example, the Hitler Youth Movement warping children as young as 4-5 years of age.
Anything, in my opinion, related to any religious belief whatsoever SHOULD NOT be a part of the FORMAL education of children even in Schools, etc, operated by Religious Institutions,

this absolutely shouldn’t be allowed. i would encourage teaching kids about the religions and beliefs of others, but that doesn’t mean forcing or leading them into practicing a ritual like this. i don’t see how it could be considered any different from a teacher leading a class in prayer. i don’t have children, but if i ever do, i won’t want them being coerced by a teacher into practicing someone else’s religious practices.

If 'exposing' means forcing the kids in a way or another to participate in or have compassion with the ideals of that minority's religion then No. Is it legit? Nope! No matter what minority it is. Most religions and ideologies are already implemented in the so called cultures of their followers. You will need honderds of years to again purify the 'culture' from its religion which might never be achieved.