I remember reading that poet Bhushan was a bard in the court of king Chhatrashal. In one poem, he wrote that gods Brahma, Vishnu and Mahesh get afraid and run away when they see Chhatrashal coming out with his weapons - clear case of exaggeration. It is possible that Chandar also exaggerated Prithvi's qualities.
Moreover, research shows that "Prithvi Raj Raso" has changed over the years.