It's not making Android more open that leads to the punishment here. Google made Android more open when they open-sourced AOSP; they made it more closed when they prohibited manufacturers from actually forking Android in a way Google doesn't like. The behavior that is punished is the use of their market power to negate the open-sourcing, not the open-sourcing itself.
They are free to fork Android though and use it however they want, as Amazon did. They just can't install the Google Play Store without including the other Google apps which Google claims are part of a unified experience.
