Insight is not buying what the Prisoner is selling. Especially after walking into the open so boldly. Where are the mind controlled slaves? Being alone suggests this might be a true attempt at diplomacy, but.... that would be done earlier without luring them here. There's something very wrong here.
Prisoner's words are a callback to page 38 where Grace asks, 'why can't we be friends?' Is this the clue that tipped Insight to the Prisoner's intentions? Nope. She attacks immediately. The Prisoner is acting like someone who is stalling to her.