Of course, it is not going to stop being UNIX, except for the little detail that POSIX is mostly irrelevant for what is sold on Apple store for any kind of their devices.
This is the ecosystem that Apple and developers that buy into Apple ecosystem care about.
Those that were buying Macs to do GNU/Linux work were a welcomed addition in times of need, that is all.
I advise reading books like The Cult of Mac and Folklore.
AppKit apps can and do interact with POSIX APIs all the time. Apple can't just pull the rug out from under them like Google might do with Android apps, for example.
Can you make an application on Linux using POSIX APIs? How about on Android? Your argument seems to be macOS is not a UNIX because POSIX doesn’t specify a GUI toolkit, but this is quite frankly absurd.
What is absurd is the way every UNIX afficionado is trying to turn my words around.
I talk about the culture of the application developers and what Apple developers that are on the platform since the System days care about, and keep being told Mac OS X is an UNIX.
Of course it is one, that is not the point being made.
This is the ecosystem that Apple and developers that buy into Apple ecosystem care about.
Those that were buying Macs to do GNU/Linux work were a welcomed addition in times of need, that is all.
I advise reading books like The Cult of Mac and Folklore.