Some of the tension in Cipher Nine's stance eases out at Clark's response. It was his reaction he was most concerned about.

By contrast, Ed's getting increasingly more tense as they proceed down this corridor. It's not the images that are bothering him, but the sounds of pain and anguish coming from the voices. As they reach the door, his tension definitely increases. He has only one real secret that he's still keeping, and he's still concerned that revealing it will mess up the Kent family's timeline. So when they get to the door, he remains silent for the time being.