The fact that Lucifer stays silent throughout the whole thing, watching without comment, is enough to put Dean's teeth on edge. There's too much silence and not being able to throw his voice into the ring as a provided distraction is almost painful. It makes it that much harder to assess the situation, try to decide how he's supposed to get down onto the floor from where he's situated. Which really just means he's not overly inclined to do it without a hint of coercion.

Finally staring straight back at Lucifer, settling back pointedly, Dean finds it harder to move the longer he waits. He's fully aware of who's going to win this staring match, but it doesn't mean he's not willing to play.