Lorna and Pietro would love to have a fuller relationship with their father. Honestly, as much as both of them have embraced Xavier's and the mission there, if Erik really wanted to it wouldn't take much have both his children following him where ever he wanted them to.
Also, I see know reason why Magneto can't be running the school now/soon. I'd like to see the difference if he was in charge and Charles was gone. He ran the school during the good half of the New Mutants because Charles was in space. Maybe Charles had been getting his Lilandra messages for a while and agreed to go with her, but just told everyone else he was going to spend time in England. It's not like people in this universe don't know about aliens - thanks Loki. Also a possibly Phoenix plot point.