Really? The whole point of the enies lobby arc was WG trying so hard to get blue prints to pluton and failing. Why would they need that at all if vegapank can just create it himself?
Ask yourself the same question since they do have a weapon which they just showed this Chapter
And no, WG didn't want Pluton Blueprints, it was Spandam's Plan, Gorosei weren't that interested, he basically wanted to trick them too
And why do you think Orochi wanted Vegapunk even though he believed no one can defeat Kaido including WG?
We've already seen lot of Geniuses, but Vegapunk is even more, he is only one who can create Ancient Weapon Level stuff