Not all warnings can be trusted, especially when someone is trying to drag you in a war that they want to find. She had a legitimate concern.
The real problem here is that she acted on blind faith; you can't negotiate with someone you don't understand. I mean, her whole plan was: we tell them that we don't want to fight and they'll agree not to attack.
Honestly, I think she's too young, and the society she lives in - closed off, with diverse people living in peace for so long - has given her zero chance to understand what the humans could possibly want. She has no idea why wars happen and she can't even understand the concept of ethnic cleansing. Being ignorant is not a sin, but not when you don't recognise your own ignorance.
Consider also, that she may be the figurehead of this foolish peace plan but the majority of votes went her way, so she wasn't alone in her way of thinking. So yeah, I do think they're all very stupid for this.
So personally, I do have sympathy. I really don't think that was is happening to her should ever happen to anyone. I would also always be careful about blaming the victim.
Also, maybe we weren't shown how the MC argued his case, but what we saw from him was not convincing at all. I am not surprised at all that his warning fell on death ears. Of course, it's not like I expect him to be a skilled orator and debater, but personally I feel like he dropped the ball really hard here. It really isn't that hard to give examples of human wicked acts and to ask: how do you negotiate with people who just want to kill you?
