The analogy doesn’t really hold. Is a bathroom door at a grocery store called a “window” rather than a “door” if they prohibit you from bringing unpaid groceries through it?
Not all windows are doors. Don’t worry about it, I’m terrible at analogies that make sense to anyone (including programmers, sadly). And if I clarified I’d just be attacked further for not endorsing the OSI party line when it comes to these things. It’s not you, it’s me, etc.
It's not open for them to use.
To argue otherwise is to confuse a window with a door.