The Galaxy S2 runs Gingerbread - It has not a darn thing to do with Windows. I wouldn’t utilize a Microsoft product even if my life depended on it.
Gingerbread Android is open source and licensed under GNU - I can take it and use it on any of my personal devices that I want (commercial restrictions would obviously apply). I don’t need a license, I can go in and tweak the kernel - all to my heart’s content. Try that with a piece of garbage Windows or Apple product.
To answer your question - you paid for the circuitry and plastic of the phone, not the kernel.
Android is a proprietary version of Linux built and *owned* by Google. Just as proprietary as iOS and OSX. OSX, by the way, is built on BSD open source. You can download the SDK and build an app and sell it tonight. That’s what I do for a living and Apple has made me quite a good chunk of change. You don’t like them: fine. But don’t go all Obama and tell lies. You alter the the Android kernel and you void the warranty. You alter the OSX kernel and you void the warranty. Same thing. You can’t download a legal version of Android and install it on any device you like. I *can* install OSX on any piece of hardware I want because I paid for the privilege.
I like Linux. I like Android, though I hate Google. I love Apple and would piss on 0bama’s shoes given half a chance.