You're arguing semantics. Windows definitely isn't open the way GNU wants things to be open. It may not be open like you define open. However Windows does have

You're arguing semantics. Windows definitely isn't open the way GNU wants things to be open. It may not be open like you define open. However Windows does have some open properties [1] that are at risk of being taken away. When we say open in this context, we mean those properties, not that Windows is licenced under GPL 3. [1] The primary open property in question is the ability to build, distribute & run apps on Windows without even notifying Microsoft. The opposite of a walled garden.