Of course, in reality, Xuannu has the background of the 'gate' on that side. The Taoist physical body she used initially was probably not a normal human from Earth. Therefore, the Bixia Sect's cultivation method, by the later stages, is likely impossible to master regardless of gender. But just as Song Dayou said, if it's only used for foundation building and then later converted to practice Taishu methods, what you practice in the early stages doesn't matter.
However, Li Fan specially arranged such a child-binding style initiation ceremony for Zheng Zetian to probe and study Luo Zu's understanding of the Dao of the virtual stars. No matter how Zheng Zetian cultivates, he will carefully ponder the other's intent.
From the principle of cultivation, this Heavenly Element skill essentially absorbs the Zixia spiritual qi, refining it into a cyan-green Bixia qi.
