He's just lost his JB on his iPhone - the worst thing that can happen to a JB dev. Last time I lost my JB on my iPhone5 (it was exchanged by Apple because of the infamous iPhone5 battery problem bricking my first-batch iPhone5) I stuck for almost half a year without any chance to work on my Call recorder muter / configurer app.
(Incidentally, this is why I try to develop / test my own tweaks on genuinely re-JB-able models whenever possible. Too bad it's sometimes impossible; for example, with the iPad + iOS7 combo, where the iPhone4 cannot be used for development.)
BTW, he has just announced the price for the app: $10. Hope it'll be tied to the Cydia login and not the UUID of the device (making it possible to install it on my several iPads), unlike some other, high-profile tweaks.