They do take patches on the drops that they have open sourced - http://source.android.com/source/submit-patches.html

Many people had similar arguments about how GCC and glib were developed back in the day (specifically, that the GCC team wouldn't take patches).

People didn't like it, and ended up forking because of it. No one argues it wasn't Open Source though.

> But Android is not an open source project. Because Google does not open its development to external contributors, nor do they develop it in the open. They only do code drops. They don't take patches.

Ignoring for a moment the fact that the factual assertions you make are completely untrue, to subjectively label something as not "open source" because you don't like the manner in which the source code is released publicly in accordance with free and open source software licensing is absolutely ridiculous.