“Wait Gandhi, we should do it when he’s in the middle of world class fight with an emperor we don’t want to anger. We should also kill one of our best agents!”
He probably only just came up with this a couple arcs ago. So the problem arises is that he needs Luffy to awaken to beat Kaido. But then people will be like wtf is this it makes no sense. So he is left in a spot where the only people that would have info on the fruit is Shanks and the WG. Shanks obviously is not involved so it has to be the WG