Han might be useless, and unable to help his kids in their battle against a Dark Lord of the Sith, but like hell was he just lingering uselessly. He had a gift for Exar Kun.
He remembered what Luke once told him about the danger sense. If it was directly aimed at him, the hostile intent would clue him in. Yeah, well, if it wasn't aimed at him, or if it lacked hostile intent, he wouldn't catch it. So he had a present for Kun, but it wasn't aimed at him. With deliberate spite, Han aimed for the a spot that would have plenty of pain for Kun, but wouldn't kill him. He let loose the concussion missile.