But of fucking course he's doing it because of it lmao. There's no need for Dragon to say it out loud, it's confirmed by the actions of his subordinates who operate on his terms and conditions. They've freeing the slaves in the Holy land because that's what their leader would want, remember how the initial operations was to declare war and rescue Kuma. If Dragon founded the WG and triggered all those wars for a personal vendetta he might literally be the most evil person in the OP world. All of the supporters see the organisation as one that fights for the sake of freeing lives. There's no other reason for it.
Dragon is fighting the WG because the CD stand in his way of freeing the people of the world, both objectives are entirely the same.
Fujitora works for the CD but upsets the entire system for the inside out. It's the best way to change the world while keeping his peers like Aramaki in check and influence what they're doing directly. You're just hung up on the fact that Fuji is being payed by the Celestial dragons, that doesn't make him a supporter.
Then we can end this discussion because we definitely won't find common ground. Fujitora to me is the greatest revolutionary in this Manga, he has learned the things the hard way and went out to do what he can with the limited resources that he had. Dragon is just a mass murderer that wants to take over the role of CD because he thinks he can do a better job. He just wants the power and authority that the CD have. Freeing a couple slaves won't make up for the millions of deaths he's looking over because it hurts his ego.