In the first place, all information that we obtained about demons came from that website. It was Nico who brought me to all those demon locations, and it was the website that became his source of information. His explanation is valid, so far.
"I went around town and killed five demons by myself. I know that it was dangerous, but the situation demands it. And you were… busy fighting the most dangerous man alive, and I should've been there to fight with you."
"Nico… Even if you were there, nothing will change."
"And who decides that?? I have knowledge, Elizabeth. I know I can do something."
Nico said so angrily, and I can't help but feel annoyed. No matter what, Nico can't do anything against Ezekiel. He might be high on his horse for being able to defeat one of the strongest demons there is, like the 'A' class fire demon. But in reality, Ezekiel is nothing like those demons.