According to Osho, entering the fifth body does not bar future physical rebirth. Reincarnation depends on vasana—residual or consciously adopted intention. A liberated being, like a Tirthankara, may deliberately bind a vasana to assume a gross body again for the dharma of guiding others. Thus return is possible, chosen through purpose, not forced by ignorance.
Even a very advanced soul can choose to be born again by tying one clear intention—like a Tirthankara does to help others.