I don't see the slow down you refer to.
You don't seem to know much about software development cycles either.
I think Michael has managed to add a lot of new features for the next release; Scene management, layers etc... were all critical to have in Moi.
There were also a lot of small changes throughout.

A big advantage of this being as you call it a 'pet project' is that Michael is very quick to respond to user's requests and adapt moi accordingly.
Try this with larger software companies. I find the term slightly demeaning though, considering how professional the development and the product are.