According to Osho, Ravana was indeed a knower of Brahman, and he enacted his role by God’s will, not personal choice. In the Ramlila, Rama and Ravana are collaborators, not true enemies; enmity is dramaturgy. Ravana’s surrender—being slain by Rama—brought liberation. The teaching: drop choosing sides, see life as divine play, and perform your given role totally, egolessly.
Ravana knew God and was acting the role God gave; life is a play, so don’t take sides—just do your part well without ego.