^ Maybe he's either:
A) Taking an unnanounced break
B) Having some RL situations that is impeding his progress (but still working on it), and again, not telling us in the process
C) Doing his progress secretely, and waiting for a big surprise
or D) Something happened to him, that he decided to give up, and let someone take the baton and do what he was doing before with this project.*
*From scratch, of course.
Those are my possible theories.