Halakhah zu Wajikra 16:21

According to the Meshech Chochmah, the permission to eat non-kosher foods is implicitly discouraged by the Torah, not unlike the Torah’s implicit discouragement (see Rashi to Devarim 21:11 s.v. V’lakachta) of engaging the eishet yefat to’ar described in Devarim 21:10-14. He understands the permission as a concession to the yeitzer hara (evil inclination; see Kiddushin 21b) and as something that maximum efforts should be made to avoid. The Rambam’s permission might be compared to the permission to eat on Yom Kippur granted to the one bringing the sa’ir laAzazel (see Vayikra 16:21-22) to the desert cliff. The Mishnah (Yoma 66b-67a) states that food was offered him at each of the ten stations located on the route from the Beit Hamikdash to the cliff. The Gemara (ibid.) notes that no one who walked the sa’ir hamishtalei’ach ever partook of the food on Yom Kippur but the very fact that it was permitted to us helped them because of the paradoxical principle of eino domeh mi sheyeish lo pat b’salo lemi she’ein lo pat b’salo: one who has the option to eat cannot be compared to one who does not have what to eat. When one is given the option to eat he is less desirous of the food than he would have been had it been forbidden to him. Similarly, it is possible that even the Rambam believes that the Torah permits the soldier to eat non-kosher food when behind enemy lines in order to (paradoxically) help him resist the temptation to eat non-kosher food.