Key word: rumors.

The Resistance doesn’t believe it’s Palpatine at first. Hence why Poe says: “We’ve coded the intel from the spy, and it CONFIRMS the worst: somehow, Palpatine returned.” Implying they didn’t believe it was Palpatine at first.

Regarding Finn and Poe, neither of them are spies. Also, I feel like they have to do their own missions and stuff pre-TRoS, post-rumors/broadcast.

Regarding the silencing thing and preventing new alliances, then I don’t think there’d be any point in wanting to get more resources and make the FO a true Empire.