[Raak] I know you're not fully taking the position that there are naturally some people with greater moral authority, but it's interesting to compare with the libertarian worldview which (without knowing much about it) I would have thought would rely on the idea that morality is personal and subjective.
As you say, it doesn't advance things much to suppose there are those with moral insight, since it's basically a deferral of the question about the source of any objective morality. For "God", read "the enlightened". You thus can't move on to asking "how does one acquire moral insight?" without committing to the belief that there is such a thing, so a leap of faith would seem to be required. Definitely not one I'm prepared to make based on my experiences.
[Bm] Moral propositions (in the view I'm setting out) aren't true by virtue of being believed, they are true objectively, and those able to see them believe because they see them. How do they do this? Well, how do you (for example) recognise the ordinary physical objects around you? There's no "how" involved that we can say anything useful about (at least not until non-invasive brain scanning technology improves in resolution by many orders of magnitude). The same for moral perception. How people get to be able to have moral perceptions is more answerable in the here and now: upbringing, spontaneous revelation, or learning from enlightened people. [Projoy] If there is such a thing as moral authority at all, then some people will have more of it than others. I don't know where that "naturally" comes from: if it's an elite, it's one that anyone can join, the same as authority about temporal matters. There is indeed an act of faith involved: the faith that there are objective morals. But there is also an act of faith involved in the perception of physical truths. The main difference between the two is that most people's physical senses function at a high enough level that it is easy for all to agree on simple physical statements, while the same degree of consensus is lacking in the moral realm. One difference, at any rate. Another is that people are much more attached to their moral judgements than their physical ones.
[Raak] True, there needn't be a "naturally" although of course in the case of perception of reality there are real reasons why some people are naturally better at intuitive perception of reality than others (a minor example is perfect pitch). We don't necessarily know the nuts 'n' bolts reasons for these differences but it is something we can say with some confidence based on the level of agreement about reality and different people's success at perceiving intuitively that which we can independently verify: I sing a note. JLE says it's A, I play an A on the piano and it corroborates his statement. But crucially his doing this does not allow me to learn perfect pitch from him. If accurate perception of some kind of objective morality is a higher order skill of this type, it's then a reasonable speculation there probably is a hierarchy of people's ability to perceive moral absolutes.
In the case of morality this strikes me as considerably wilder speculation than making the same statement about perfect pitch. This might be for anthropic reasons, of course, but if so your line of reasoning becomes rather depressing for those who don't sense an objective morality, since it suggests they are missing something big and are never going to perceive it! (Slartibartfast would say, "Oh, no, that's just paranoia. Everyone in the Universe has that.")
...and of course something else follows from that line of reasoning, which is that if one is to have the best system of law, there are objectively people who are qualified to legislate and indeed, such a thing as government with objective moral force, whom we lesser mortals are insufficiently equipped to judge!