That there is a threshold, and that Ardyn has found it, is telling. At the time, there had been a faint voice in the back of his head that had wondered if perhaps even knowing everything he did that maybe he had gone overboard in the man's murder. With this knowledge that he's being given, he can quite soundly put that thought to rest.

Combine that with the Scourge, well... Perhaps he did only the bare minimum.

But more importantly than that...

"Ill in what way?" Ignis asks, in a quietly dry tone that says, actually, bullshit that is the only side-effect of something which warps people into daemons who have no hope of becoming normal again.