Because he did the mistake of neglecting, at least in thought, his duty as a king for a short time since so very much he would have liked to run away from the life of a king and to be free from all royal obligations only once - to live at least for a short moment like the wise saint here in the deep contemplativeness of his life in wisdom - he feels within himself a deep guilt from that desire which violated his duty, and therefore the king deems himself not worthy of accepting the offer of the sage.

“In front of his own sons and soldiers he wants not and must not admit this mistake; because it is part of his royal duties not to weaken the existing order of his realm.

Therefore, in front of his retinue, he declines the offer by claiming that catering was too much effort for the sage - a fact that is perfectly true from the side of the king, because from his point of view it is too much effort for a great sage indeed to feed a warrior who has lost his duty from sight, even if only for a moment.