Aaron was absolutely emotionless during the verdict reading, but did anyone keep watching? Once the judge started thanking the jurors for their service and started talking about how important it is for citizens to accept the service they served, THEN you could see the emotion start to hit Aaron. He mumbled something, started looking down shaking his head, kept looking around all over the room... all little things, but FAR more emotion than he displayed during the verdict reading.
It's like it just hit him as the judge was talking to & dismissing the jurors.