The guardsman is polite throughout Rhy's explanation. He is almost too polite and is listening quite carefully. If Rhy is perceptive, he may notice the guard expresses a small amount of surprise. It's possible he expected another diplomatic tactic rather than Rhy's sincere reply.

He will ask next why Rhy believes an investigation would be necessary when Thorne has found, as they officially claim, solid evidence of the "specific malefactor" on one of their own Summoned. The guardsman appears to be using this term to refer to the nation responsible as a whole, not an individual.