So your argument is that an Admiral betrayed the Navy and started a Revolutionary Army, becoming the most wanted man in the world, and the World Government kings just didn’t hear about it? Lol
Not everyone is as dumb as you are, if an Admiral became a WG traitor then the WG kings would most certainly know about it.
One: Again, nobody even knew who Issho and Aramaki were, lmao, it's not impossible that some people weren't aware that Dragon was a former Admiral, especially when you consider my next point..
Two: The WG and Marines actively cover up shit like that, they were afraid of admitting that Luffy beat Croc and Doffy and not the Marines, to the point where Akainu banned Issho from coming to any Marine bases after he let them beat Doffy and admitted that they did it.
Furthermore they also didn't say anything about Issho freeing slaves at Mariejois, or Garp and Roger helping each other molest Rocks and the Holy Knights(?) at God Valley.
They're not going to say anything about a former Admiral revolting and trying to overthrow them, that shit would hurt their public image too much.
Also I forgot to mention this but I don't feel like editing it into the second point, but Imu and the Gorosei were extremely pissed about Wapol and Sabo knowing about Imu's existence and what they did to Cobra and Vivi.