Ask Sister Mary Martha: Michael the Archangel, NonPerson

I haven't had a chance to check Sister's blogs for a couple of weeks. I truly appreciate everything you've shared regarding St. Michael as a confirmation name!!!!!!!!!!!! Thank you so much for all of the information and advice you have provided! May God continue to bless you as you share your wisdom with others!
Ask Sister Mary Martha: Michael the Archangel, NonPerson: "I have quite few questions waiting to be answered, but this more recent question has sparked quite a bit of righteous indignation from the..."

St. Michael the Archangel

My son's religion teacher (Catholic) won't allow him to choose Saint Michael the Archangel for his confirmation name.  My oldest son chose this saint when he was confirmed in 2007 with no concerns at the same church through a different teacher.  Her reasoning is that he is/was an angel not a person. 

I am frustrated with her insistance that this saint is not acceptable as a confirmation name choice.  After hours of searching the internet I have been unable to find any catholic website or information suggesting that this name is not appropriate for confirmation.  In fact, I have read many church approved web-sites that recommend this saint's name as a confirmation choice. 

If anyone can find factual information regarding this issue I would be very grateful!

Thank you in advance for your help!