He would not have noticed on his own; he isn't even looking at her, among those with his back turned. Nor is he trying to assist with the argument between the two camps. Even if Kostos might be the most objective and reasonable person here (and he is, just ask him) all it would take is someone recalling his family name and the circumstances of their exile to make things worse, actually.

He doesn't know how to talk to people, but he knows how to not talk. So that's what he's doing. Listening, his quiet foreboding in a way that makes anyone unlikely to try to loop him into any debates, his mind wandering —

to the spirits housed in the mummies Teren is screwing with, experiencing flickers of their muddled perspectives as if it is his own, and he turns to stare directly at her.