Well, to be specific what he says is that she's causing an imbalance, and to stop the physical and aetheric laws of the world from being corrupted Hydaelyn needs to be "burned out like a parasite." What exactly that means is... still up for debate.
Regardless, Hydaelyn (God, or at least our creator) tells us not to listen to what they say, and given their highly malevolent actions thus far I don't see much reason to do so. I'm willing to hear them out, but it's pretty tough to justify things like Cartenau.