Rhys agrees to omission over straight up lying. It's not that he's against lying, but that being caught lying could be worse for them and they don't/can't know what everyone knows.

Rhys will confirm that the Almagoras is aware of his empathy, but he isn't sure if the Dragon is. However, the Dragon seemed to know a lot about Rhys in their brief encounter, so Rhys would err on the side of probably yes.

He would also agree to the idea of acting out noticing Riona's doubts for sneaky purposes. Acting can fool empathy (we've done it on screen a few times in non-serious applications /o/) as long as it's method acting, though unless Rhys is sharing what he's feeling by touching the dragon/masked man, there's no way to prove what he's sensing to them. He could still act alarmed/surprised/worried by her himself though.

Exceeept they expect him to have his own doubts. (And he does, just not doubts enough to murder anyone.) This may be enough for him to reveal his own mother was Almagoras-- provided Kata/Lera/Vanya don't see him thinking about it and stop him-- but not that he took after her magically, and that the enemy knows.

(If his explanation of empathy makes it unappealing for her plan, he'll skip any reveals.)