Yatsushiro Yuzuriha and Komikado Nerine are the enemy?!

Shocking revelation just happened with Suou properly deducing that Yatsushiro is the source of the letter that was sent to discredit and damage her that I talked about in the previous post. She initially thought there was some secondary reason for this, some key or information to be given, but according to Yatsushiro herself in this scene, it was purely to stop her from trying to get closer to the "goddess of truth". What is this goddess of truth is unknown, but I guess it's related to why Mayuri is basically hidden somewhere...
Both her and Nerine acted almost like different persons. Nerine especially was acting like the typical annoying and irritating guard dog of Yatsushiro with spiteful voice acting (really good job on the voice artist here). And well, they did something that is basically nonredeemable in my eyes. They shoved Erika to the ground for no reason whatsoever. I mean I'm sure nothing bad will happen to her, but the very act of doing it knowing the possible consequences is just a big nono regardless of whatever thought they may have had.
Seems like they are on the villain side this time around and I'm stoked now to know exactly what they're hiding. It's the first time in the series that there is a clear cut villain instead of just misunderstanding and similar things.
What does Dahlia knows about this is the question. She clearly knew that Yatsushiro was the source and stopped Suou from saying her name when she confronted her. And yet she does nothing, just watch the things unfold...