Respect for people

Many thanks to the Rabbi for the words:
1 Regarding the Maimonides, the words are indeed explicit, for he said: "And why was the return of a lost thing rejected because it is not of money?" Apparently, you should say more strongly that it is a return and do not do, and also include prohibitions. And also regarding the rest of his words, he is speaking specifically about someone who loses the Passover sacrifice in favor of impurity for a deceased who has performed a mitzvah, and not in general, as one might understand from the Gemara in every case of returning and not doing anything.
2 Regarding the extent to which the lenient is, I saw in Macropedia that there are opinions that even a no is rejected in the case of standing and doing something: ”And the first and last wrote that according to the Yerushalmi, the honor of the people rejects the mitzvah of the Torah, not doing anything, even in the case of standing and doing something (Hashokel [Retzb”a] Hilchot Tumat Kohanim (p. 178), and the commentary of R”sh Cyrilio and Pnei Moshe Berakhot 3, end of Halacha 1, in the Yerushalmi Berakhot opinion there; R”sh Hilchot Kilai Bagdin 6, in the Yerushalmi Berakhot opinion there; Shailat Ya'evetz 2 Qe'ach, and more).
And there are some of the first who wrote that even in the opinion of the Yerushalmi, there is no honor for the people that rejects the commandments that do not do anything except standing up and doing something (Or Zura'a 1 Hilchot K'laim Retzt), and that they permitted the priest to be defiled by the impurity of the Torah for the honor of the many, not with impurity that they certainly permitted, but with doubt of impurity (commentary by the author of the Haredim book to the Yerushalmi there),
And I am only asking what is accepted as halakhic according to the Rambam, as I understand it - that he did not permit doing something even in vain or according to the views that are lenient that reject even doing something even in standing up and doing something. In short, how far are they stretching the curtain on the matter? Many thanks to the rabbi

1. It is possible. There is evidence here and there, which is discussed in the aforementioned aharonim. In any case, as far as I remember, their claim is that this is a disagreement between Rambam and Rosh, and you can check for consistency.
2. I have no idea. If you are asking about Rambam's method, I don't understand what answer you expect. You are asking what the aharonim said about his method? In any case, this is their opinion and not his. Beyond that, I didn't understand the question, because you yourself said that in his words it is seen that it rejects only a prohibition in vain.

I ask whether there is a particular line that has been accepted as halakhic by the rabbis of our time? Mishnah, Aruch Shulchan, Rabbi Ovadia, Rabbi Auerbach, the prophet?

I have no idea. According to your opinion, the Rambam believes that he does not reject a prohibition in vain, and certainly not in a qu'a. And as for the rabbis of our time, I think it is common to think that he rejects a prohibition in vain (I can't say whether he did or not). But this is not necessarily related to the Rambam specifically.

I found a specific definition in the Mishnah 2
Shulchan Aruch Orach Chaim Laws of Tzitzit, Section 13, Section 3
If he learns on Shabbat, while he is in Carmel, that the tallit he is wearing is invalid, he should not remove it until he reaches his home, and the greatness of the honor of mankind. The thought: 7 Even a small tallit (11) that does not need to be removed under his clothes. And if one (12) has stopped wearing [8] tzitzits and is ashamed to sit without a tallit, (13) he may wear it without a blessing, (14) according to the power of the honor of mankind (2) in the name of repentance. And precisely on Shabbat, (16) it is forbidden to wear tzitzits, * but on a day when it is forbidden to wear a tzitzit, it is forbidden.
Mishnah Berurah, Section 13, Section 9

(15) And precisely on Shabbat – Pi’ According to the Shevshabbat Litha, only the prohibition of the rabbis is as above, but on a day when he transgresses a Torah prohibition at any time... and a Torah prohibition, even just a prohibition of deshb and al-ta'esh, such as preventing a person from performing a mitzvah, is not rejected out of respect for human dignity unless it is a great disgrace, and therefore it is forbidden to wear a tallit when one sees that it does not have a tzitzit delishb without a tallit s'l Ram'a, which is only a small disgrace in general.

I don't see any definition here that you can learn anything concrete from, and certainly not according to the Rambam's method. It is clear from his words that in his opinion, the dignity of mankind does reject the prohibition of not doing wrong, and this is not according to your Rambam's understanding, but according to the Poskim. However, if it is a question of not doing right, he writes that a great disgrace is required. What exactly is a great disgrace? I don't know. I remember that Rabbi Asher Weiss in Manchat Asher discussed this at length: https://minchasasher.com/he/shiur/%D7%A4%D7%A8%D7%A9%D7%94-%D7%A9%D7%99%D7%A2%D7%95%D7%A8%D7%99%D7%9D/%D7%92%D7%93%D7%95%D7%9C-%D7%9B%D7%91%D7%95%D7%93-%D7%94%D7%91%D7%A8%D7%99%D7%95%D7%AA-%D7%AA%D7%A9%D7%A2%D7%95/

Thank you very much.