Dragon left the Marines when he realized how evil the group they were serving under was. So I am asking once again why is Garp not a huge fucking scumbag for playing the Marines and WGs favorite propaganda tool for several decades despite knowing very well how awful the Celestial Dragons are?
Garp looks more and more like a worthless stooge every chapter man. Either he declined to join Dragon, or he was not even asked since Dragon knew his father did not have the spine to stand up against the World Government. Either way? Garp is a disgrace to the Monkey D name. Only D member we know of that willingly serves the WG to this day.
Just imagine what kind of legitimacy it would have given Dragon and his rebellion if Garp, the Marine hero, who stood beside his son and said "the reason I never became an Admiral is that I would have to protect a Celestial Dragon if they cam to harm. They are pure evil and need to be replaced for the world to stand a chance at improving!" the Rebellion might have already won by the time Luffy sets out to sea.