I think that counts as a mutant. Mutations are not always positive, and I don't just mean the comic-booky ones. The Elephant Man was a mutant, after all. According to the dictionary, here's what a mutant is: "An animal or plant with inheritable characteristics that differ from those of the parents". So, if my parents both have brown eyes and I have green ones, that makes me a mutant - and presumably, this poor guy being a disfigured freak makes him a mutant, too.