Why should they have to agree with that though? Franklin is a whole child, the current version of him have never gave a damn about the mutant plight. He got the message same as everyone else and for whatever reason he ignored it. Now their trying to force their ideology on a child it's just not a good look. Especially when he has loving parents who have already gave their answer on the subject.
They literally just have to wait 2 more years for him to become an adult then they can approach him all they want. At this moment in time it's just not the move comes off very culty... Just Saying *shrugs*
Maybe Xavier should be more focused on trying to find/be a father to his own child while he's trying to convert other peoples kids. And maybe Eric the holocaust survivor should recognize the hypocrisy of trying to split up a happy family.