Long winded responses are fine, I write them fairly often!
The issue concerning Omega here isn't really "do you want her to be one," it's what her not being considered one means in connection to how else Marvel treats her. Hickman's rules don't say the character must already be the most powerful in their area, and they don't say only one mutant can be Omega (two mutants are deemed Omega as telepaths). They only say the mutant reaches an undefinable upper limit. In Lorna's 616 history, earlier stories said she has the potential to surpass her father, stories like The Twelve implied she's already his equal power-wise, and some issues of her on Genosha outright said she may have surpassed him already (though in fairness, his powers were weakening toward losing them at the time).
Maybe Magneto is better at using those powers, but Hickman's rules aren't based on years of experience or "featz," only raw power.
I see two "outs" for this. One is creating this classification to deliberately tear it down later. The other is to couch it in Xavier's mindset, saying he made the list, as that allows who is and isn't on it to be a matter of story and Xavier's opinions rather than "this dude who works at Marvel decided this thing because reasons." I could consider the "[KNOWN]" label to be an out too, but honestly I think that's just prep by Hickman for introducing powerful mutants later. Not a means of saying already known mutants may apply but aren't listed.
In the end, it's not the status of Omega itself that matters to me here. I think classification systems of this type are junk and shouldn't exist. All it does is create unneeded fandom infighting and place artificial limits on characters. But because this system does exist, we can look at it for what Marvel thinks of characters. For Lorna, it says a lot when you combine it with all the other ways Marvel ignores and excludes her.
Regarding Exodus, it's supposed to be the natural progression of characters, but Marvel's decided it doesn't apply to Lorna, otherwise she'd have the same things Exodus does or equivalent. Lorna and Magneto being "redundant," again, does not apply here by Hickman's own rules. Magneto being considered Omega certainly hasn't held him back from having major roles and activities, why should it be any different for Lorna?
Regarding the cover, "daddy gets rid of terrible ex" is exactly the problem. Lorna's a grown woman who can make her own decisions and fight her own battles. The cover frames her as weak and powerless, lacking agency for herself and requiring a man to come to her rescue. It would have been fine if it was something more like Lorna and her father fighting side by side against Havok and his team, but that's not what they did. They cast Lorna in the role of damsel in distress for a man to save her. It's bad no matter who the man is.
Imagine if this was Jean on the ground with Cyclops and Wolverine fighting over her. Or Storm on the ground with Black Panther and some other character fighting over her. Don't you think that would lead to all sorts of outrage? Why would it be unacceptable for them, but fine for Lorna?
Finally, Lorna and Krakoa. If Marvel behaved differently, it could be a great place for her to shine. But everything we've seen, both for the past 5 years and from day one of HoX/PoX, has been the opposite. She was used in HoX and X-Men #1 primarily for men to talk at her about things relevant to them. An X-women variant cover left her out completely, but included other characters like Dani Moonstar and Magik. Her history with Genosha and Krakoa hasn't been mentioned or used even once so far, while other characters like Storm get to act outraged about the millions of deaths she never personally saw but Lorna experienced firsthand and had replaying constantly in her head until she was recovered from Genosha's ruins. Then there's the Omega thing.
If Marvel had acknowledged her history at various points this past year, it might have been possible to say "Okay, so it took a year, but maybe they just had to figure out what they wanted to do with her." That doesn't explain the X-women variant cover, which demonstrates how little they think of her despite being the second woman to join the X-Men. It's not like they were struggling to squeeze characters in. All it would've taken to give her room was placing Shadowcat closer to Storm.
It also doesn't explain why she couldn't show up visually in scenes where relevant, or say things relevant to her in the two issues that she had some panels. If you look at just one thing in isolation, it might seem like nothing. It's when you look at these things together that you see a pattern.