I think your discussions of metaethics might be improved by rigorously avoiding words like "fair," "right," "better," "moral," "good," etc. I like the idea that "fair" points to a logical algorithm whose properties we can discuss objectively, but when you insist on using the word "fair," and no other word, as your pointer to this algorithm, people inevitably get confused. It seems like you are insisting that words have objective meanings, or that your morality is universally compelling, or something. You can and do explicitly deny these, but when you continue to rely exclusively on the word "fair" as if there is only one concept that that word can possibly point to, it's not clear what your alternative is.

Whereas if you use different symbols as pointers to your algorithms, the message (as I understand it) becomes much clearer. Translate something like:

Fair is dividing up food equally. Now, is dividing up the pie equally objectively fair? Yes: someone who wants to divide up the pie differently is talking about something other than fairness. So the assertion "dividing the pie equally is fair" is objectively true.

into

Define XYZZY as the algorithm "divide up food equally." Now, is dividing up the pie equally objectively XYZZY? Of course it is: that's a direct logical consequence of how I just defined XYZZY. Someone who wants to divide the pie differently is using an algorithm that is not XYZZY. The assertion "dividing up the pie equally is XYZZY" is as objective as the assertion "S0+S0=SS0"--someone who rejects the latter is not doing Peano arithmetic. By the way, when I personally say the word "fair," I mean "XYZZY."

I suspect that wording things like this has less potential to trip people up: it's much easier to reason logically about XYZZY than about fairness, even if both words are supposed to be pointers to the same concept.