It discredits them because they claim to be politically unbiased and only trying to expose corruption of others but they got caught lying in order to make The Post look bad and make the women claiming Moore assaulted them look less believable too, exposing them as politically biased and corrupt.

They intentionally tried to set up The Post to make them look bad in order to prove their own point (which in itself invalidates their point) and got their asses blown out. Go look at the Project Veritas entry here to see what I'm talking about, I just put that in the notes for context.

As a bonus, since she's literally proven to be a liar and Moor is claiming he'd sue people who made false claims, this puts Moore in a pickle. He can sue them alone, but cause it to be connected back to him. He could sue no one, and have people point out that this person for SURE is lying. Or he could try to do what he originally claimed and sue ALL of them, but have everything get dragged out in court publicly and forcing people under oath.