פירוש על עבודה זרה 58:7

Rabbi Joshua now provides another reason why non-Jewish cheese is forbidden. Non-Jews use rennet that comes from calves that were used in idol worship. Since any item that was used in idol worship is forbidden to a Jew, non-Jewish cheese is forbidden to a Jew.

Rabbi Ishmael responds that if non-Jewish cheese is forbidden since it may contain rennet that comes from an animal used in idol worship, then it should not only be forbidden to eat, it should also be forbidden to derive any benefit from it. From the example in the previous mishnah concerning Bithynian cheese, we learned that the Sages said it was only forbidden for consumption and it was not forbidden to derive benefit from non-Jewish cheese.