Heh. You haven't seen her pull off her "Acrofatic" maneuvers at your shrine, fumeiyano inu, the sort that the original Brand wouldn't have dreamed of trying. She's learning how to properly use Brand's body with her own talents and skill. And she has passed many tests since being forced to flee from Laputa. She's a very squishy (ahem) dragon mage.
Unfortunately, that does not mean Suzocon is wrong. But, while he does not speak outright lies, he speaks with two tongues, twisting the truth into whatever shape he needs it. Interesting that instead of just brute forcing the situation, he's subjecting Saida-hime to the same sort of mental twisting he's giving Roko.
Obviously it's in his interest that she doesn't rat him out to Retanlong, or get to his charging machine (i.e. Brand) first. But... aren't there more expedient ways to do that? What is his game here?