Oh, I'm sure there's nothing secret about that gratefulness. But it's also trivial to dismiss: The Fire Phone flopped badly. While people buying Kindles mostly just expect to be able to read Kindle books, you cannot sell an Android phone today without the Play Store and be successful.

The law is not like programming, if something is 'technically true', it's probably false as far as the law is concerned. The law is much more concerned in this area with what is 'practical'. It is not 'practical' to fork Android, and operate as a business with it.