MDG,
I never meant to say that R’ Moshe reconsidered or contradicted himself in any way. Only that the practical application of the heter changes based on the circumstances.
I think that “ba’al nefesh yachmir” meant even if difficult.
You ask which yechidim he refers to, and I think he means the general population, as opposed to yeshivos.
I agree that it’s possible to understand it the way you did, but besides the fact that I think my way is the simpler way, it also conforms with the other two teshuvos.
I still see no reason not to accept the other two teshuvos, especially the one from the ????? ??????. The fact that it was not printed in Igros Moshe is immaterial; many of his teshuvos were not.