It's not nitpicking.
Google could close source Android (or make its own OS since the license for Android probably prohibits this) and just customize it for the OEMs themselves based on requested specs and get a similar result.
If everyone who uses Android didn't use any of Google's proprietary products, Google has a noticeably less amount of cash coming in.
Android is FOSS, yes. But the key to Google's success with it wasn't that it was open, it was that it was cheap/free and good(the primary reason their closed software has the penetration that it does: it's cheap/free, and good).