Oh, for God's sake. Did they both forget what Seth's power is? He may not be extremely keen on dragging both of them through a dozen walls, since that seems like it would get very exhausting very quickly.

"How about I just..." he says, sticking his hand through the door close to where the handle is. He feels around for a bit on the other side, dragging Peter's hand a bit. The chains go through the door, but Peter's hand doesn't. It only takes a couple seconds for him to find a latch and push it open with a satisfying click, before pulling back his hand.