The joke part was that Stark could manage it. Coulson had particularly mixed feelings about that member of the Avenger Initiative. However, he had no doubt Hill would beat him senseless if he was foolish enough to get killed again.
Coulson did manage a smile though. “It was the right call. Asgard is better equipped to handle it. Loki is too dangerous to keep in our custody.” He put a hand in his pocket, shrugging slightly. “Did they scrap Phase II finally?”