Avira, I was concerned that you misuse Rema with an emphasis that Torah debates presumes striving for Emes rather than showing off sources for your side. And the more you know, the more is your responsibility to stay with emes. This is not controversial, this is throughout mesora.
On Igros Moshe, there are several teshuvos. I looked just at one, I think he is suggesting several possible shitos – whether we accept that Rambam, and your conclusion is only under one of them.
I personally have no questions on R Moshe’s shita at the time & place he was. It is hard to put oneself into a different circumstance or to prove that to others, but I was, for about a year, part of a remote community that had no leadership and learning, and I spent a year running a school’s Jewish dept, leaving math to others, even as I was more qualified to run the math dept. I don’t even remember who was running the math dept, I had my priorities straight.