Da, the ponevezher rov did not believe in nationalism, as in the idolatrous belief that klal yisroel is a nation by virtue of anything besides the Torah. Nor did he think that Hashem supports the reshoim.
He had hakaras hatov for having a place to live relatively safely after the war. Nothing more. Talk to any ponevezher talmidim – and look who succeeded him as rosh yeshiva! There were never any fundamental disagreements between the rav and rav shach.