A Spiritual Palace could be understood as many things, but the way Di Tou fundamentally understood it was as a memory. A core memory that one manifested into reality, and because it was the memory of the Spiritual Palace Stage expert and not anyone else's memory, only the creator could properly visit it and control it, thus creating an absolute safe space.
Of course, Di Tou's Spiritual Palace Stage had gone awry just like Mu Di Bai's cultivation had gone awry, although both in different directions, so despite Di Tou's understanding, he couldn't really apply it or test it out.
