a) I was making a rhetorical point.
b) In reference to MDG: I am trained in academic methods, so perhaps I am influenced by the approach of Haym Soloveitchik, Professor Israel Ta-Shma, zt”l, Prof. EE Urbach, zt”l, and others who utilized a contextual approach to the study of halakha.
c) A rishon cannot disagree with the Talmud because everything up to and including Ravina and Rav Ashi is binding. The shitot of the Rishonim do not have the valence of canonical Torah, as the Talmud does.
d) The Rema’s approach on these issues is similar to how Tosafot view clapping on shabbat and mayim achronim, how Rabbenu Tam views gevinat akum, and how Teshuvot Mayim Hayim views women’s hair coverings. These are approaches which render psakim either on the basis of human need or changing social circumstances which contravene actual halakha as presented in the Gemara. (See Hakham Yosef Faur’s article on The Legal Methodology of Tosafot in Dine Yisrael for one explanation).
e) On Nat bar Nat: The main point here is whether you can be somech on nat bar nat l’chatchila. Nobody disputes it b’dieved, including the Rema.
But what do Ashkenazim do with the shita of the Darchei Teshuva? Here we have an Ashkenaz posek who says b’shem the Siftei Daat that if something parve is cooked in a meat pot, then only the klipa is assur to eat with halav. And, also, the Shach is more machmir than the Rema, and says that the tzalu is assur even b’dieved (unlike Rema).