Except that the young O5 won't be attacking Magneto, they're seemingly going to defend Emma from him, so Lorna wouldn't imho go through the young O5 to help Magneto get to Emma...
Maybe initially but long term I doubt that she'd fight the young O5, and if anything she'd probably try to stop the fight and figure out what's going on, not sure that she'd just buy that the young O5 just up and attacked Magneto out of nowhere...
I will agree to that Abnormally, just saying that it'd be a way to split Lorna and Magneto without making them enemies or fighting just that Lorna would stand up for her views and Magneto his and they'd part on if not great at least amicable terms as if Marvel is putting Magneto back onto the bad side I don't want Lorna to follow him...and who knows she might be on that other team in Astonishing...not the Astonishing team itself though the other one in that book...