He said he'd open source it, but it never happened. I think this pre-dates Mojang, but I'm not certain about the exact timing.
http://web.archive.org/web/20100301103851/http://www.minecra...
http://web.archive.org/web/20100301103851/http://www.minecra...
"Once sales start dying and a minimum time has passed, I will release the game source code as some kind of open source."
So he can release it as open source, to make good on what? Some "About" page he wrote fucking 4 years ago when Minecraft was nothing but a PC indie sleeper hit?
Get real.
Especially a promise to a community that throws him under the bus whenever something happens they don't like (even if he isn't involved)?
I don't think that is reasonable.
"Once sales start dying...as some kind of open source".