Just being open source should not provide blanket immunity. This is also hardly some small, independent developers we are talking about, they are very large international companies. IIRC Android Alliance rarely, if ever, accept 'independent' contributions, it is just a dump of source code when they feel like it (Android 3?).
I am a big fan of open source but I totally disagree on this specific case.
If you are big fan of open source, I would suggest you to consider diving into source and send a few patches. Because AOSP receives about 100 independent contributions every month and almost half of term are merged into the master tree.
I am a big fan of open source but I totally disagree on this specific case.