Yes, I get what you’re saying. But it’s different in Lorna’s case because while she isn’t one of the original 05, she is one of the oldest(not in age)X-Men, she was there after the 05, but before the Giant-Size X-Men including Storm and Nightcrawler. She joined the X-Men in the late 60s, she was one of them captured by Krakoa. And besides Lorna isn’t Jean with that ‘good-goody’ nature, but she isn’t as extreme as Magneto is sometimes she kind of resides in the middle,(so she would likely at times vote agaisnt and with her father and it would create some small conflict) like Emma and Mags she survived the Genoshan genocide, and she’s led teams successfully and efficiently before. And even if in your opinion it wouldn’t be fair as a whole or make that much sense, in terms of Magneto’s character it would make a lot of sense...he would basically have his own faction. With himself, Lorna, Emma(kind of), Exodus, and Namor(if he joins the Council)...and this might create conflict if and when the whole secret about Moira comes up.
Although I see your point about the whole monarchy thing it’s valid. But Lorna was a very early X-men as many forget. So she would abide by the ‘rules’ of Summer. Although I admit I am biased, because I love Lorna(not as much as her father and a few others but I still took love her and I am biased)and I recognize this probably won’t happen and Marvel will probably choose Beast(for conflict) or Iceman(to represent LGBTQ+ and for funny elements).