It has stuck in my head for a while now - roughly quoted as saying that one shouldn't mock minhagim that have developed in klal yisroel even if the origin seems dubious - as Hashem wouldn't allow pointless or harmful minhagim to fester among his nation just trying to follow halacha and mesorah - so any minhag is by definition with hashem's haskamah.
Something along those lines. 90% sure it was chazon ish, couldn't find in his igros though...