Nonsense - Android's userland does not use GNU, at all; or Linux display servers; or the POSIX standard; or anything but the kernel. Apps on Android have no access, or ability, to directly call kernel functions. Android is deliberately designed so the kernel could, hypothetically, even be replaced one day without breaking anything.
Forcing apps into an abstraction layer from the kernel is good design, preventing kernel quirks from being permanent features. Not using GNU is another design choice which can be debated, but it's completely valid, there's no requirement (moral or otherwise) to use the GNU userland with the Linux kernel. Most embedded devices also eschew the GNU userland by instead using Busybox.
Forcing apps into an abstraction layer from the kernel is good design, preventing kernel quirks from being permanent features. Not using GNU is another design choice which can be debated, but it's completely valid, there's no requirement (moral or otherwise) to use the GNU userland with the Linux kernel. Most embedded devices also eschew the GNU userland by instead using Busybox.