Responsa sobre Baba Metzia 7:14

They responded: even though this is permitted, we only share this ruling with the pious, lest it is seen is public and the masses come to transgress.^*The language of the question comes from a responsum of Rav Saadia Gaon, who forbids this practice of asking a non-Jew to buy on Shabbat. The responsum is quoted by the Rosh on Bava Metzia 7:6:1, and although Saadia's reasoning is rejected, it seems that he agrees with the ruling - although maybe the ambiguity reflects something of the answer given here.