Azh, the Reb Moshe you quote is very shver, and I doubt you could defend it. Not that I can challenge Reb Moshe, as I am not a moreh horaah, but if one learns the Rambam, there is certainly room to ask questions. The Rambam (Talmud Torah 3,10) writes kol hameisim al libo sheyaasok btorah vlo yaaseh melachah vyisparnes min hatzedakah harei zzeh chilel es hashem ibazah es hatorah vichavah maor hadas vgaram raah latzmo vnatal chayav min haolam haba…kol torah sh’ein imah melacha sofa bteila vgoreres avon, vsof adam zeh sheyehai melastem es habriyos. He goes further in (3,11). He also says in (3,6) lo alecha hadavar ligmor, implying it is understood that in olam hazeh it is difficult to learn kol hatorah kula and one is not expected to finish, just to do his best, given the constraints of parnasa.
If Reb Moshe would have said that we don’t pasken like the Rambam, or that it is eis laasos lashem, and we must violate the Rambam, fine. But what bothers me is how you can learn a pshat in the Rambam which is 180 degrees the opposite of what the Rambam says in black and white. I don’t see how the Rambam could have made it any clearer that he feels one should not be somech on his learning for parnasah. How can you say that the words KOL hameism al libo sheyaasok btorah vyisparne min hatzedakah…KOL torah shein imah melacha sofa bteilah… means that one is mechuyav to support himself from tzedakah if he doesn’t know kol hatorah kula or will not be able to know kol hatorah kula if he works. Do you mean to say that this halacha only applies to one who has already learned Kol Hatorah Kula? Why didn’t the Rambam tell us this himself? This is probably the most shver Reb Moshe I have ever seen. If anybody can say pshat, please do so.