I'm the developer from Insurgent Games. Thanks for explaining the licensing details so well. I've just updated the readme in all git repos at https://github.com/insurgentgames to include a licensing block that says:

This game is licensed under the GNU General Public License (see gpl.txt). As the copyright owner, I hereby give anyone permission to re-license my GPL code under a non-GPL license for the purpose of distributing it in the iOS App Store or the Android Market.

So people are welcome to fork my project and still publish in the App Store without even having to contact me.