I'm not sure if you're trying to bash Microsoft here or not, but I'm going to assume you were genuinely curious. The reason that most people are following him

I'm not sure if you're trying to bash Microsoft here or not, but I'm going to assume you were genuinely curious. The reason that most people are following him (anecdotally anyway) is that he's a well known (the most well known?) and successful person in the tech space who has just joined. There isn't any reason why he can't turn off seeing "@ replies" from people he doesn't follow either - doing that will only show tweets from people you follow. Twitter's settings are pretty configurable for users who have tons of followers.