Dont take anything literally. The esoteric meaning of Immortality or Amrutatva is attaining Self Actualisation. He attained Self Actualisation at 16. Was a genius, a Master of the Intuitive Sciences & Arts Liberating, So when the Ex KIng and EX Bizman wanted to hear about the Greatness of the Mother Divine, Devi Mahatmyam, they were lucky to hear it from the lips of this Divine Sage, Markandeya Maha Prajna/ Sarva Sastra Visharada / Srotum Ichami Asheshena / Devee Mahatmyam Uttamam.