IMO and IME, not to poo poo anyone, however from watching him in court in other hearings, I've noticed that is the face BK tends to have when listening intently to being directly addressed by the judge. I have also seen AT touch his arm like that in a previous hearing to get his attention when he is listening to someone else.
If he had been acting aggressive in that moment, I can guarantee that one of those two officers would have had their hands on him, not the casual stance they have in that image.
I went back and looked at the video. Right as the camera was turned off after the judge announced court was adjourned, BK and AT stood up. Right as the camera turned off, she put her hand on his upper arm as the two officers were walking towards him. BK kept his eyes on the judge as he stood. I believe this shot was taken a second after the cameras went off.
IMHO, in that photo it feels to me that the the judge was giving BK some final instructions and the officers were waiting for the judge to finish. I believe AT put her hand on his arm to let him know the judge (from her experience) was likely going to give him some final comment and to wait there.
*shrug* Sorry.