Kyo wants Gregory to try to win him over to his side? The doctor has no interest in Katherin or Kyo just the information. He is convinced that there is little chance that Kyo couldn't possible have the information he wants. But he knows there is a good chance that Katherin does because as the keeper of secrets she had access to EVERY secret within miles of her. Your right that just because secrets know doesn't mean Katherin does but that is alittle too logical for our villain.