User blog comment:IamJakuhoRaikoben/Chapter 503: The Last Sight Seen, Review./@comment-4945830-20160926222531/@comment-75.175.68.80-20160926230751

Well when you think about it Zeref was cursed by the powers of a god so Natsu being able to counteract age seal makes sence as age seal is also magic that comes from a god as well.