He brought them so he could just have a panel saying "this invasion is no joke".
Then just casually turn the pacifista army against them, and bring in the giant pirates for more Nika worship.
Came to Egghead to learn about Kuma's big secret and Vegapunk. Only to learn that Vegapunk worships Nika, Kuma worships Nika, Bonnie worships Nika. Now the giant pirates are here to worship Nika, can't wait for elbaf "the great Usopp arc" .
grow up fools, that's a Nika worship arc too, better hope Sanji doesn't get hype tooled by Loki, and Zoro isn't "stalling" Baldur for 30 chapters after Nika low-diffed him earlier in the arc.