According to Osho, the 'one percent' impurity is the compassionate tether that keeps a realized master visible and accessible. If he were 100 percent 'alcohol' (pure divinity), he would vanish like God, losing contact with seekers. That residual desire or bondage forms a living bridge, allowing the master to serve as vehicle, medium, and guide between the absolute and humanity.
A tiny bit of “not-perfect” keeps the master here so we can see, relate to, and learn from him; otherwise he’d disappear like God.