I have a setup where I share a screen between two computers (a macOS productivity machine and a Windows gaming laptop / x86 VM lab). I did look at a lot of tools to be able to disable one of the screens in macOS so I wouldn't need to fiddle with cables, and I remember that this one didn't work.
I use mirror-displays[1] (alongside Bunch, which also turns on VBAN Talkie for audio) now. Mirroring a screen is the only way to approximate disabled screens.