No, Mihawk isn't more influential than Buggy. Buggy's clearly the more influential individual but the thing that threatens the WG most i.e., the real reason why they consider Buggy that big a threat is Mihawk while it's the other way around for the Yonko. They consider the Yonko commanders a bigger threat because they've got their captains while it's the opposite for Buggy and Mihawk, and hence Buggy can't have an influence on Mihawk's bounty, not to the same degree as Yonko and the Yonko commanders.
