Exactly. And the point of standards like OStatus (and it's component specs) is that we don't all have to be using (or contributing to) the same software... instead we can build a myriad of apps that work together.
Of course. They (StatusNet) were actually the authors of it (I believe). I'm not against having multiple implementations by any means.
It just seems very knee jerk to start your own so quickly. "I hate Twitter. Hey, use my version of Twitter that's open, but allows you to sign in with Twitter."
Then again, he might have decided that StatusNet has too many dependencies and was looking for something super simple--I don't know.