When people say linux, they don't care what kernel they're running - they mean GNU/Linux that has a reasonably close interface to that of a typical UNIX machine. I agree with Stallman &co. that the name "Linux" is imprecise, but you shouldn't pretend you don't understand what people mean.

Android systems don't run normal Linux binaries; Android has an incompatible ABI, not least of which because it puts the dynamic linker in a different location (and compiles that different location into every single binary). It shares the same kernel, but with a completely different userspace, and typically requires a separate effort to port.

(I'd have said "GNU/Linux" to avoid the ambiguity if I didn't think it'd massively and pointlessly derail the conversation. In particular, given the nature of this thread, it seemed needlessly adversarial.)

That's a bit like saying that all Xbox users should count towards Windows numbers.

Google patches the snot out of the Linux kernel in Android. In fact in now contains a fair amount of ideas from OpenBSD. Theo De Raadt talks about some of the in his Pledge talk: https://www.youtube.com/watch?v=F_7S1eqKsFk