That has nothing to do with open software.

So it's not open.

I think you are twisting the definitions pretty hard. Android isn't open for anyone who also wants access to the dominant app store. If you want that and sign that agreement you can no longer effectively enjoy the right you have under e.g. the GPL and distribute devices with modified versions of the code. As I understand this is legal under the GPL, but certainly very shady towards the developers who made the code available with the intention for it be used openly, rather than being leveraged by Google for their anti-competitive means. Also those practices is preventing other developers, who has as much right to the code under the license, from using those manufacturers. This is a clear attempt of trying to use their dominant position to control the market and shut out the competition from those manufacturers, not just controlling the manufacturers themselves which would be bad enough in the first place. And that is exactly why they are being and should be fined.

Windows is also open. You can do whatever you want, it's just if you want their stuff (except .NET and Powershell), you play by their rules.