I mean, sure, I've seriously weighed the benefits of using Mr. Nibbles as home defense, especially whenever I read about the latest spate of home invasions... unfortunately, it turns out the bad guys have already had similar ideas about robbing people at snakepoint:
http://www.snopes.com/critters/gnus/snakerob.asp
Though bad guys will use just about anything. Apparently frozen squirrels also make effective weapons:
http://www.snopes.com/critters/gnus/squirrel.asp