I can’t see why Mihawk or Weevil would join him.
What if, the WG actually became smart, and made a deal with Buggy, the WG would help him reach Yonkou status by notoriety and territory, in exchange he would be an ally of them.
We already have spies in the form of Stussy and XDrake, not to mention Mother Carmel being connected to CP 0 itself, the next step would be to propel up a harmless Yonkou, so they can tighten their grip on piracy.
Kaidou, Big Mom and Shanks were also shown doing deals with the WG, so this modus operandi would not be new.