People are completely missing the point here. “Who made Red Hat the arbiter of when Xorg should end?”
I would say nobody but perhaps a better answer is all of us that have left the work of maintaining Xorg to Red Hat. All that Red Hat is deciding is when they are going to stop contributing. So little is done by others that, if Red Hat stops, Xorg is effectively done.
Others are of course free to step up. In fact, it may not be much work. Red Hat will still be doing most of the work as they will still be supporting Xwayland ( mostly the same code as Xorg ), libdrm, libinput, KMS, and other stuff that both Xorg and Wayland share. They just won’t be bundling it up, testing it, and releasing it as Xorg anymore.