Calling Android a "Linux distribution" is entirely misleading.
When you refer to Android as a Linux distribution, it is entirely misleading. You can make an argument that it's technically accurate, but it is still misleading.
Traditionally, the phrase "Linux distribution" has not referred to the kernel, but to the operating system sometimes referred to as GNU/Linux. It is true that it has sometimes been used to refer to embedded systems that technically weren't GNU/Linux, but were only API compatible with it. Those systems, though, still used the same software as GNU/Linux and still 'felt' like GNU/Linux.
Android has made no effort to remain API compatible with GNU/Linux (much less ABI compatible). Applications for GNU/Linux must be ported to work with Android. It's clear that Android is a different operating system than GNU/Linux. Also, there are distributions of Android, like Cyanogenmod and various manufacturer's distributions. Even if you were to argue that Android distributions are Linux distributions, it wouldn't make sense to call Android in general a Linux distribution.
Calling Android a "Linux distribution" ends up being inconsistent and only serves to confuse the uninitiated (I've seen this happen). It is much more straightforward to refer to Android distributions and Linux distributions as separate things. Then you only have to explain that the operating system which people refer to as "Linux" is really just the first operating system based on the Linux kernel, called GNU/Linux by some, and that Android is another operating system based on the Linux kernel. As confusing as that may seem to some people it is much less confusing than trying to explain the inconsistencies involved in referring to Android as a "Linux distribution."