Steve, I have never heard this side of the story before. I have no sources lending support to that idea but I can show an account available on line that points the finger at Banks's troops. Here is the link...

http://www.libertychapelcemetery.org/files/a_burns.html

You have my interest stirred. Are you involved with a project you can tell us more about or is this just personal interest? I believe the occupations and burning of Alexandria would be a good subject for a book. You would be a good choice to write one!