It is true that Rovio isn't forced by anyone to create a GPL version or to release their code. I should have pointed this out. However, their options are pret

It is true that Rovio isn't forced by anyone to create a GPL version or to release their code. I should have pointed this out. However, their options are pretty limited, considering they want to make money off of the software. They could simply stop distributing it from the platform. But they want to make money, which means that they(presumably) want to get as many sales of the game as possible on as many platforms as possible. However, if the main system interface is GPL(and not LGPL), the GPL does not allow anything to link against it that is not GPL code. So, given that, they are effectively forced to do it if they want to get any further sales and ad revenue on the Android platform, because they would not be able to distribute the game in it's current version.