Journey to the West: The Big Boss Behind-the-Scenes

Astounding!
Tang Monk unexpectedly declines the pilgrimage for scriptures?!
Sun Wukong, astonishingly absent from beneath the Five-Finger Mountain?
Guanyin Bodhisattva: "Is Tang Monk not destined to retrieve the scriptures? Why refuse the journey westward?"
Buddha Tathagata: "Is this muscular bald man truly the reincarnation of my disciple?"
Jade Emperor: "I merely smile without words. Relax, it's just a smile..."
Who is orchestrating all of this?
Li You: "You guys really wanna know? Do not regret it!"