Why wouldn't it count does Aokiji immense strength and level of danger he posed as marine suddenly vanish when he became a pirate
But that has nothing to do with serving marines, that's just based on how strong he is.
Meanwhile Mihawk was pirating for decades and was hunting marines and now is one of the leaders of Cross Guild that put up bounties on marines.
If Kuzan gets anywhere near Mihawk's bounty or higher while only pirating for 1 month, any admiral bitch diffs Mihawk.