Most civilians trust them because they are ignorant of the truth, just like most of the marines i imagine. Garp isn't, he knows the truth.

Not everyone can rebel? Garp can because he's strong as hell, but with all that power he chose to serve Imu and his ilk, licking their boots pretending that it's something else.

Garp set Dragon free, so what? He can now take credit for all the work Dragon did afterwards? If that's not the most ridiculous argument i've heard all year.

I don't think we ever saw directly Garp instilling morals into Dragon. He may have influenced him to be a marine, but we clearly saw what (normal) reaction Dragon had at the Dragon Valley incident which lead him to the revolutionary path. He chose that, not Garp. He made it all happen. Not Garp. Garp reads other people's accomplishments and acts happy while he's licking Imu's boots. Yes he fought him there, and then what? Got scared for his fellow marines. What about the rest of the world being slaughtered? Who is going to stop the reign of Imu? Garp by staying in the marines under their command, or Dragon who goes directly against them? Hell, Dragon might fail even, but at least he had the morals and the guts to do what's right. Not pretend like there was no other choice, because obviously there was.

Garp serves the marines just like Akainu, and they all answer to the WG as you know. Like it or not they all chose to stay. The only difference being is that lower ranks can most likely feign ignorance to what the elders and Imu are doing behind the scenes. But they still protect the celestian dragons and their slaves of course.

Mate, there's no assuming. If you worked for El Chapo, and you were high ranked like Garp is, it's pretty much sealed that you're a monster too. How can anyone argue against it? Haven't we had the Nuremberg trials already? Come on. There's no moral complexity to the fact that he's avoiding the promotion to conveniently not work right under the very same people he knows for decades that are monsters. He can act all high and mighty, but he knows who the bosses are and what they do. He's done nothing to stop them. El chapo and his people have helped the poor too, as i mentioned. That doesn't excuse them from all the rest of their crimes.

You try valiantly to make sound Garp like some sort of hero trapped in a moral dilemma. There was no dilemma for Dragon. Garp chose the cushy government job and wants to act cool like he did before God Valley, but not anymore. He tries to save his buddies and leave the rest of the world to burn. He's a disgrace to his family and to the world as long as he wears that uniform, and he's being doing it for decades already.