Exactly.
And the Moon Is the closest planet to Earth/Imu in general and in the geocentric model too:
Garling Is the reason behind GV, which was the reason why Dragon turned againt the WG in the first place.
He was also the "husban" of the woman Dragon found and tried to help and the father of the two children he tried to save in GV.
I think Dragon vs Topman made sense before, when Dragon didn't have any notable connection with any of the Gorosei and so him vs the most notable Gorosei made sense.
Now not only the most notable Gorosei is Garling (Moon and so on), but Dragon has a personal plot connection with that Gorosei.
Not to mention Garling Is a much more important character than Topman: