Y'all know I'm a mihawk fan.
But what if Mihawk personally went to Luffy after WG asked him to?
But he reported he found no one , because of Zoro.
Rather he went to shanks to report it.
Live action I know ain't canon , mihawk went there from Marines (Garp order).
Point was Nika elimination that's why WSS was chosen to do so.
Mihawk observed Luffy in Marineford too and tried to personally intervene making it look like he's attacking him but actually saving him due to shanks request or something and once he arrived , mihawk left.