According to Osho, Valmiki’s “writing” Rama’s life beforehand is a profound joke: Rama, as a man of maryada—strict code and restraint—was so predictable that his script could be drafted in advance. It wasn’t literal foreknowledge, but a metaphor for a fixed, serial existence where each response—Sita’s abduction, agnipariksha, banishment—was predetermined. Krishna contrasts as unpredictable.
It means Rama followed rules so tightly that anyone could guess his choices, so the poet described the pattern—not the future.