Marvel operates like other creative companies, where they refuse to admit when they do anything wrong unless they’re forced to do so. In this case, restoring the twins too soon after regaining the film rights would be implied admission that the retcon only happened because of their spat with Fox over film rights. Kills the false pretense they gave of “we think this is the right way to go with these characters for story reasons.”
So, Marvel’s gonna wanna avoid addressing it for a few years. Until they can claim the retcon was a genuine attempt at storytelling but now they’ve decided the twins as Magneto’s kids is better.