WHO'S SURPRISED?

In the last trailer there is a scene where one of the alien humanoids' is in the chamber that houses the gun/telescope/thingy. He's either about to pick up or has just placed the glowing green orb. The gun thingy starts to rise out of its hanger and he looks very surprised to she it coming out of the floor, his whole body language says this is unexpected. Could it be that David is in the SJ suit, now infected with the grey matter and an "artificial person", has interfaced with the biomechanical ship systems and is about to interfer with the "Engineers'" nefarious plans for humanity?