I mean it is a flag in a field that isn't short of flags. No one else wants that flag. It hurts no one to use that bit.
So there is no valid technical reason to exclude the flag and there IS a good reason to include it, just as syscall, ioctl and device numbers have been reserved in the past. So that new feature patches don't get created that use the same bit. So that future authors writing out of tree code don't end up with a user-space that has to be recompiled when they merge other kernel features.
Objecting to the "process violation" is one thing, and perhaps deserves a post or two. But what then? For ignoring the bureaucracy it seems people want to administer "punishment" by not including the flag. Which is ridiculous at this point because by NOW there HAS been a lot of discussion. Linus has reviewed the patch and accepted it. So the discussion has all been done and the "process" has been successfully followed.
And FYI, code gets changed by maintainers without discussion all the time. Whenever there's a merge conflict between trees is one example.