Tikkun Olam and Redeeming the Hostages

As a Dvar Torah for Vayigash (Joseph's revealing himself to his brothers following Judah's speech), I explore the mitzvah of redeeming our captives and the limitations on the law "for the sake of Tikkun Olam." The conversation among American Jews about Gaza centers around "Ceasefire or No Ceasefire? What kind of Jew am I if I don't support stopping the bombing?" while the conversation in Israel is "Exchange terrorists for hostages? What kind of Jew am I if I don't bring my sister/brother home at any cost to an Israel bereaved beyond measure?"  In an amazing synchronicity with the Torah reading, the entire drama of all the parashiyot of the Joseph saga lead up to whether Judah will say for his brother Benjamin what he wouldn't say for Joseph, that he will do anything rather than fail to bring his brother home to his bereft father, an Israel who cannot bear further trauma. What kind of Judah/Jew am I if I don't bring my brother home to my heartbroken Israel? And there is Israel (Jacob), saying he will enter Sheol (the underworld) if he is forced to endure another son never coming home. The redemption of Jewish captives is one of the hightest mitzvot in Judaism. Why? And why does the Talmud and Jewish Legal codes say that one only refrains from doing so for the sake of Tikkun Olam?