MY DDS school is visiting a gurdwara and they have been told they have to wear a scarf and bow to their religious book.
Whilst I respect other peoples right to take part in whatever religion they like, I do not respect their religion , because as a Christian I believe christianity is the only true religion.
I feel that wearing a headscarf and bowing to a book crosses the line from educational into observing some of their religious beliefs.
DH has been into Muslim, sikh and hindu temples in the courses of his work and never been asked to cover his hair, so it can't be an 'absolute' rule.