I don't see any reason why you cannot remove it.
I can certianly remove it, and do. However that means I have to open Notepad, remove the null, close, and then open the xpl in XML Notepad to edit. Since AnyDVD is already modifing the XPL file to remove the AACS header info, it would be a simple matter to remove the null also. This would save me several steps when I go to edit the XPL. I would only have to double click on the .XPL, and XML Notepad would open.
Hence my request TO THE ANYDVD developer.