No one gives a shit about Caribou, is this the guy that you are comparing with Mihawk?
Imagine being so desperate you using Caribou to damage control Mihawk's Marine Hunting.
Killing some random useless marines with no purpose is not equal to Mihawk's Pro Marine Hunting. Not even mention a weakling like Caribou is irrelevant.
He can't comprehend Mihawk gets Marine Hunting boost unlike Yonko, and being underling of Yonko also boosts his bounty, and still has much lower bounty than Shanks and BB.