I dare you to buy a random Android phone and try to get the source code for the GPU driver that will compile and match the functionality of what's installed on the device.
I don't know if you are trying to defend that "Android is not an open source OS" or if you are trying to play on words like the other poster?
The best open source mobile OS you can get nowadays is based on AOSP, where the A means "Android". Sure, there are people who make proprietary products out of that. But it doesn't mean that Android is not an open source OS. The OS part, again, is open source. Even the Android SDK is open source.