Not only is this dog a traitor to the Navy but he's also an absolute fraud when it comes to combat abilities. A hobbling Garp is able to speed blitz him when they're making eye contact and having a conversation.
The best he could do is slightly scar Akainu whereas Akainu took his leg clean off.
Out of shame, he left the navy and spent a year being an alcoholic before joining the smelliest and least presentable Yonko crew in the world.
Tbh, I'm glad he's no longer in the Navy. If he was the Fleet Admiral instead of Sakazuki, Kuzan would've lost every outpost in the New World and would be struggling to hold onto Paradise.