Despite using quantum mechanics everyday as part of my research, I'm by no means an expert in fundamental issues surrounding the interpretations of quantum mechanics, such as the multiverse. These arguments and interpretations (I would agree with Mindwolf that these are not theories in the usual sense, more interpretations of the existing theories) are more philosophical in nature. The Many-Worlds interpretation dates back to Hugh Everett III (who, in an unrelated note is the father of the lead singer of the Eels) and his PhD thesis. I would say these things are still very much on the fringe of physics and not the conventional or common interpretation of quantum mechanics. I don't think the people mentioned in the article are bogus in any sense, and certainly not armchair physicists!