I can understand why she would have been reprimanded for violations, and if she were to continue to violate the policy, then she should be fired. The problem is that there was no written policy, and she was not required to sign a document acknowledging that she was not to bring "unclean" foods onto company premesis.
For instance, if you work at a Jewish synagogue, it would not be unusual to have a similar policy.
The problem with dietary laws is that if you bring something "unclean" in and use utensils, plates, pots, or pans, you wind up "contaminating" those things. Which then "contaminate" any food used with them for others. It's a complicated matter.
My grandfather was a "Mashgiach," or one who supervises kitchens to make sure that they followed the Jewish laws of "Kashruth," the dietary laws. It's complicated, and although it may seem outdated, for those who are religious and observant, it's every bit as important as a baptism or Sacrement.
Mark
The Jewish people, so far, have not shown religious bigotry. I will respect their wishes when around those of the Jewish faith.