> But I don't have a reasonable
principle to back that up.
Sure you do. Just try to find your hidden assumptions and axioms, and try to come up with alternative ones. Remember, for every reasonable assumption, the opposite assumption may be just as reasonable. In this particular case start asking yourself what does a "favored class" mean? Who favors it? Why? How is the class formed? What does "protection" mean? From what? To what end? Why is that end desirable (or not)? And every time you deem something good (or bad), keep asking yourself why, until you get to your personal set of axiomatic values[1]. Of course, when coming to a question of fact ask yourself, am I sure this is a fact, and if so, are there possibly other pertinent facts that I may be unaware of?
> Can you?
I can easily, but I could also come up with a reasoned argument to support your point of view[2]. The result in this case, as in many others, is fully determined by your choice of axioms.
I could fully argue both sides of any ethical debate, but I support the one side whose required axioms coincide with mine. I would like to believe that my personal choice of values (which has changed considerably over the years) is at least partly a result of my effort to study society in earnest (i.e. semi-professionally), and my values are almost universally shared among those who have spent years studying society, while those with opposing values usually have not. So I can only hope that my values are supported by some measure of external "truth", but, of course, I can't say that they are objectively more "correct" than yours.
BTW, I'm not advocating for randomly chosen favored classes, but for protecting all groups that are disadvantaged by our current choice of economic structure from further unfair harm which said economy may inflict on them.
[1]: And don't just say "freedom", because freedom alone is a self-contradictory value (there can be one completely free person, but not two) that must be further qualified by other values. So if you think freedom is your only axiomatic value, try harder and you'll find more.
[2]: Pretending, of course, that you'd chosen a better example than Jim Crow, where members of the favored class were former chattel slave owners who "protected" themselves from treating as human the multitudes of victims they had violently abducted and robbed (and raped and killed) for two centuries to enrich themselves. But I think I can see past that poor choice of an example to understand what you're getting at.