I wonder if they considered Xamarin?
Another big language at Google is C++, which also has a cool cross-platform client story. Emscripten for web, Android NDK, iOS can use C++ libraries directly.
I do get the security part, I also like how both Android and Windows Phone 7/8 share architecture ideas with IBM i.
However, it would be nice to also expose the framework to the NDK without forcing everyone to write their own bindings.
Or at very least, expose other Android internal C++ libraries like SKIA, as part of the public NDK APIs.