Although Xue Fanxin wanted to save the people from the four great clans, she was unaware of the ethereal realm. She was outside the illusion. If she wanted to save the people inside, she had to break the illusion first.
This illusion was created by the Spacetime Emperor. How could it be so easy to break?
Even if it was, she could not do it carelessly. If she let those ungrateful bastards escape too easily, they would not feel thankful. She would wait until they were at the moment of life and death. Only then would they remember her kindness.
This was like giving a steamed bun to someone who was about to starve to death. He would feel indebted to you. However, if you gave it to someone who was not hungry, he might not be grateful, even thinking that this was a form of charity and not a favor.