[tienshiao]

id Software is also the copyright holder of the games and can choose to license the game or parts of the game out however they want and as often as they want.

They did have the occasional issue where they were using comercial libraries and had to take those out of the codebase before they could open source them.

In this case, the theme developers are not copyright holders of the WordPress code and thus are subject to the WordPress.org's license.