He may still possibly be working on the project... Or abducted by aliens. Or simply burned out. He did mention an injury a long while back (nearly two years ago) where his work slowed considerably, so, maybe something with that? But he's never said directly.
Sadly, he hasn't given a reason why updates are taking longer, nor any information on his (or the game) status. So, all we can do is guess. He has been radio silent for more than six months, and while not his longest absence, that is quite a while. So~ maybe more from him? Maybe not...