Rabbi Kanievsky's military service

The public is talking about ultra-Orthodox rabbis who served in the IDF.
Famous among them are the Rebbe of Seret Wiznitz, who fought in Haifa, or the Rosh Yeshiva of Tifrah, Rabbi Aviezer Piltz.
For some reason, the military service of Rabbi Kanievsky in the south, guarded by the Egyptian army in 1788, as well as in the hills east of Petah Tikva (now Rosh HaAyin-Kfar Kola, which he inherited), is being downplayed. As a former son of Barak, the rabbi knows why?