Can a person’s conversion be revoked if he converted based on an assumption that is now considered mistaken in his view? (Maimonides does write in the laws that this is not possible, but there I think the intent is to a righteous convert who remained in his belief and wanted to return to the status of a resident alien—but what about a convert who became Jewish because he had high expectations of the religion in certain matters, and later discovered some flaw? For example, the story of the failure involving Yuval Dayan: a non-Jew from Russia converts because he thinks the rabbinic leadership and Haredi society are the height of morality and glory, and then after 28 years changes his mind and declares that he no longer believes in God—can his conversion be revoked?)

I already answered that. The only possible revocation is when it becomes clear retroactively that he was mistaken at the very moment of the conversion itself, not when he regrets it afterward. If the conversion itself was done on the understanding that the Jewish public was more moral, because he was entering that public, and it became clear to him that this was not so, then his conversion is void. But if he is now unhappy with what he discovered—then he’s stuck with it.