Why does Eris meet with Rhysand and Cassian at the Spring Court in Chapter 14?

Eris meets with Rhysand and Cassian at the Spring Court. He thinks they are wasting their time gathering information instead of acting. He thinks they should take out the human queens. He can only delay his father from allying with Briallyn and starting the war for a few months. He suggests they find a way to deal with Briallyn. Learn what she wants and why. Discover if Koschei is involved. At best, they will stop them. At worst, they will have proof to justify a conflict, win allies, and avoid the bloodshed that would carve up the lands again. His father would think twice before standing against an army of superior strength and size.