Rav Shmuel Berenbaum did not participate in anything that would take away from his shiur. Plus the Mirrers in general (including the Bais Hatalmud roshei yeshiva and people like Rav Leib Bakst in Detroit) have not participated much in the Aguda scene.
Rav Avrohom Kalmanovitz, based on the times that he lived in, (hatzolah efforts during WWII) and the environment in which he built his yeshiva, participated in Aguda type politics more so than his successors who had different battles to wage.