“Guy 1 “why are you doing [fill in the blank] it is keneged halacha?”
Guy 2 “Oh it is my minhag and “minhag trumps halacha”
DY “It doesn’t.””
I love this. This exact conversation has happened so many times in the CR.
Ubi, I think you have it pretty much right. But, don’t ever say “minhag trumps halachah” out of context. I think R’ Moshe was talking about the Litvaks who otherwise follow Ashkenzi, non-Chassidishe minhagim with the Nusach Sphard thing as a matter of being consistent. He had to know his rulings mean nothing to actual Chassidim, but might mean something to Litvaks who have adopted some Chassidish minhagim like Nusach Sphard because they like it of whatever.
DY: Could you elaborate on the clapping thing at all? I’ve noticed that Sphardim tend to clap backhandedly on Shabbos to show a difference while Litvaks don’t tend to clap at all (especially not during davening). Are you saying the Rema is the source for the clap-only-during-davening? Or that he said it’s mutar to clap whenever you want on Shabbos?