Yeah, that's the angle they should be going at.
Fictional minorities (i.e., characters which belongs to a minority which can't exists in our real world, like Kryptonians on Earth) are quite fine when it comes to dealing with some troubles real minorities suffer while the authors thinks that using said real minorities wouldn't allow for an audience large enough (If Superman had been a Black or Latino in appearance, would have he worked as well as he did ? it's debatable, at best). But when the main point of the mini-series is to highlight the viewpoint of minorities which are actively disfranchised, I don't think it would works.
However, Supergil is a woman, with all the problems it entails in our world (#MeToo anybody) ? She is at least as strong as her cousin (in some stories, I remember that it was even implied that she is stronger than him, but I may be wrong here). She has at least as much scientific knowledge as he does (probably more, since she actually studied on Krypton to become a scientific, if I remember right and could probably learn more about sciences relatively easily)... and yet she'll always play second feeble to Clark. in a sense, it's the allegory of what women suffer in a work place : they may be as competent as the men they work with, but it doesn't matter in the end, they'll be paid significantly less (as a recent scandal in the BBC revealed, for instance).