And it did work, abet in a manner they weren't expecting.The second was because the third strongest precog in the world, and the strongest known friendly precog, said it would work.
I do wonder though, did Tagg or Rebecca ask Dinah about possible consequences of playing hardball during the interrogation? I assume not, or Dinah forgot to mention that "Yes, playing hardball will get Skitter on board with the Protectorate and eventually save the world, but you two won't be there to see it."