If the X11-and-Wayland maintainers had put X11 up for adoption that might not have been the case.

That is, they might have said "We're looking for new maintainers for X11. They will be responsible for its future direction, representing X11's interests to the kernel and to distributions, and deciding when (and if) X11 is to be declared deprecated."

As far as I can make out, what they did instead was say "We're looking for people to fix bugs in X11, but they won't get to make any nontrivial decisions."