LMFAO
Coby is hero of Rocky Incident, Garp is hero of marines.
You'll find a million marine heroes of whatever random incidents. You must be on some heavy cope to think their titles are the same.
He will never surpass any admiral anyway, if someone's going to do it it's Smoker. Coby is just another Luffy fangirl who will regarded as a cute little marine who saves lives. He's just not that guy.