Earlier quoted context omitted.
Maybe but is it really a fair question? Notch wasn't the only owner. In fact, he owns less than 50% and they have 40+ employees. http://en.wikipedia.org/wiki/Mojang Open sourcing it would likely screw his co-founders, employees with stock options, etc. compared to the size of this deal. Tbh, I'd be happier if he donated 10% of his earnings from this sale to Open Source projects and feeding people. Rather than, y'know…
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...
"Once sales start dying and a minimum time has passed, I will release the game source code as some kind of open source."