If Tianxuan were to die from Heaven's Punishment, or be severely wounded by it, that would equally fulfill the Immortal Queen's intentions, and she could take this opportunity to deal with Tianxuan. If you can't solve the problem, solve the person who brings the problem.
With Tianxuan dead, all causes and shackles naturally cease to exist.
This is actually the best solution. However, after Tianxuan orchestrated the defeat of the Immortal Queen back then, she remained reclusive. By the time she met the Immortal Queen again, she had already achieved the Third Grade Dao Fruit. With third-grade combat power, if wholly focusing on avoiding battle, few could indeed restrain them.
Not to mention that Tianxuan excels in Qimen Dunjia and Yi Dao Xuan Technique; she's not some crude Martial Artist. To intercept and kill her is as difficult as climbing the heavens.
It is precisely for reasons like these that the Immortal Queen agreed to Tianxuan's deal.
