I'm not a lawyer, but after reading the patent file, it seems to me that it only covers the kernel implementation; unlike facebook patent clause which covers everything.

Right, Facebook wants to be able to do anything to your sister (or IP) it wants and you can't ever sue FB, if you dare use their code. Google just wants to trade any rights you have to the specific implementation of the code you've deciding to use. They won't sue you or you them re that specific code. Not the same universal IP grab at all.

On the other hand, change one iota and you have no patent grant from Google of any kind, I believe.