It may have been WizCo...
WizCo can't send out a C&D because Nautilus does not break any copyright laws, and the editor merely offeres the capibility of infringement.
That'd be like trying to shut down HP, Epson, Xerox, and Canon for making printers and copiers that could be used to produce counterfiet cards. It's not Nautilus' fault if someone abuses their product. (Note: Recent court cases have been alowing such grounds, and if this trend continues, noone will have any right to do anything. Just so you know...)
If WizCo sent this, it is because they know they can't stop Nautilus directly, and once the Magic-based patches get out, they won't be able to castrate their enemies like they did to Apprentice, Enchanter, and KingMagic.