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They are defining distance based on the conventional picture, then asking how fast it is increasing with time, as I mentioned in my above comment.
They are "defining " in a way, that no galaxy is bound to any visible relativistic effect. Everybody does that, albeit on at least two different ways.
How convenient!
We have superluminal galaxies, not bound to relativity. We have nearly light speed galaxies, free of any observable relativistic effect. Our hypothetical ancient space ship sent there (to a nearly light speed away moving galaxy), would slow down all its clocks, the surrounding galaxy wouldn't.
Funny.