Who else is american? I didn’t recognize any names. Sorry for my ignorance. R”O explicitly disagrees with Reb Moshe. He doesn’t misunderstand it. He quotes it correctly and proceeds to disagree with it. As an American Ashkenasy, I go with Reb Moshe.
As far as R”O’s factual premise to the psak: “??? ???? ??????? ??? ????? ??? ????? ???? ???? ???? ??? ?????? ??? ???? ?????? ??,” I’d find that exceptionally difficult analogy to apply to a gym. Even leshitaso, which I wouldn’t follow over r. moshe. So again, source?