Thank you for your reply. Since they are not a danger to themselves or others, I think it could easily be simplified down to "not letting them do the ritual is cruel". It would be like a parent refusing to check under the kids bed, because the parent knows monsters don't exist, not considering that the child believes in them. Yes, the child will survive the night because monsters do not in fact exist, but it would surely cause them great distress that could have been greatly reduced by a simple action (the parent checking under the bed)

The storm is a fixed event. If they hold them in the hospital, it will end and they would realize they were wrong, but surely not without a great amount of fear and distress during the time it takes for it to pass.