The Ishgardians and Dravanians were trying to kill each other. At times they were also trying to kill the Warrior of Light and his allies. That did not stop them seeking peace, even when it seemed impossible. Thus, by not assuming the same to be possible with Garlemald and reaching out themselves they are hypocrites - especially when they complain that Garleans are killing them when they themselves are doing nothing to ease tensions. A war that waged for a thousand years was ended. Why wouldn't it be possible to broker peace with the Empire, then, given that the war with them has lasted for far lesser a time?
War is a two way street. It doesn't matter who starts it, necessarily - because at some point so many people have died on both sides that ending it becomes a necessity. Ending it in such a way as to avoid needless bloodshed - which is precisely what the goal of the Warrior of Light and his allies should be. Instead, it feels like selfish vengeance - especially if they decide to take the fight further into the Empire's territories and refuse to acknowledge the nuances. By that logic they should have wiped Ishgard off the map - but they excused Ishgard's sins and came to understand them. You'd think they'd be bright enough to look into the 'how' and 'why', combining it with Regula's heroism and thinking 'hold on a minute...' and acknowledging that if someone like Regula can rise through the ranks and be reasonable and influential then there's probably others like him who can be reasoned with.
Defectors don't count since they have no loyalty or care for their people or homeland.
We'll see how things play out with 4.1 but...the Eorzeans don't get to play the sympathy card if they continually refuse to even acknowledge the possibility of diplomacy and peace. After Ishgard and Zenos revealing himself to be working against Garlemald's interests then there's really no reason not to try and forge some sort of treaty and/or agreement.