Noctis was surprised by the venom in Sanji's voice when he threatened to kill anyone that would starve Noctis. It caused happiness and so much guilt to bloom in the dragon's chest. Happy that he had finally found a family again that would do anything to protect him and guilt because he disappointed both Zoro and Sanji with stashing the food away. But even with the guilt there, gnawing away at Noctis, he still felt the fear of not having a stash of food to rely on.
Bowing his head in shame and guilt Noctis spoke softly but loud enough that Sanji would hear him. "I'm so sorry," Noctis said the shame in his voice, "I promised Zoro I wouldn't do it anymore." Well the promise was not to let food go bad but it was close enough for Noctis. "I will make that promise to you." He would fight his fear so he wouldn't disappoint Zoro and Sanji again.