Moses spoke to Aaron and to Eleazar and Itamar his surviving sons: Take the grain ­offering left over from Adonai’s offerings by fire, and eat it without hametz beside the altar, for it is most holy. You are to eat it in a holy place, because it is your portion and your sons’ portion of the offerings of Adonai made by fire. For so I have been commanded.
Leviticus 10:12-13 TLV

Parts of various offerings were divided between God, the priests, and the offeror. In the case of this grain offering, part was for God and part for the priests, and the priests had no say in what they were going to do with it. They had to eat it for the sake of the whole nation. Ministering before God on behalf of the people has obligations, even if we sometimes don't understand the point.