That she doesn't drop the kind behavior is even more disconcerting than the idea of it being a lie. Gale wants to ... to remove it. Either by removing himself from the situation or by removing her. Neither of which is an acceptable option, but the second is the one that Vayu is pushing for, and Gale tenses--

Argilla moves. The motion is defensive, and Gale can tell it's not the more extreme motion she wishes to make. She's restraining herself, and it brings Gale back to the knowledge that the move he needs to make cannot be the aggressive one. So he goes still, as utterly and completely as possible, for a moment or two.

Though his eyes are closed, Gale is very aware of the woman standing across from them. He's tempted to employ one of the genjutsu he's learned since receiving his Atma, but that would also be counted aggressive if it was discovered, and some of their opponents have had strong defenses against such things.

So he merely opens his eyes, calm regained, and continues Argilla's statements to the obvious conclusions. "My comrade is correct. There have never been children in the Ruins, and you do not know us to be able to compare our actions to any other individual. Desist, so that we may commence negotiations appropriately."