>It assumes those people don't already know they are being investigated
They still have hope, still think there's a chance to win
>AND that normies would even care that Huma or Pedosta were arrested.
Normies don't matter. Other criminals would know, get more serious about covering their tracks. Goal = keep them with their guard down, keep them feeling sure their massive crime ring is untouchable
>The only people in the dark are the public.
Everyone is in the dark. The criminals don't know who they can trust, don't know how much the white hats know.
>Why do they need to keep this sting hidden from the public?
Stings are kept hidden from everyone till they are done. Watch The Sting. Criminals + bystanders - both have no idea anything is even going on