Earlier quoted context omitted.
Greg KH already decides what goes into the "stable" Linux series (4.y.z, for instance 4.18.15), which is what most people actually use. Besides, he assumed after the 4.19 merge window, and he's handed the 4.20 merge window back to Linus; it's in the merge window that new features come in (after the merge window closes it's mostly only bugfixes), so it's still Linus who gets to decide.
Is stable different from latest? I am not sure how much independent decision space he has, otherwise we would have d-bus in stable long time ago. Maybe I don't know the process well enough but I would be surprised that Greg can merge something that isn't approved in latest. Fingers crossed it is only 4.19, I am kind of seeing this as a bigger event but I may be wrong.
A good number of Linux distributions are based on an LTS release instead of a mainline release.