Sounds like that guy has no real passion for any of those teams. At least not to the extent that we do (as in, people who care enough to post on message boards). I know many people that adopt a team for whatever reason and claim to be a fan, but they definitely do not experience the highs and lows that we do as passionate fans.
I believe everybody has one sports entity that they are truly passionate about. Some may have two, but most of the time one outshines the other. It could be college or pro, some may have one of each, but nobody has 2 within college or 2 within pro. And 99% will care about one much more than the other.
So what constitutes real fandom? Well, anything you want really. But I feel to be a true fan you must have some sort of a tie to the team, not just complete bandwagon.