Probably the monk from the Luo Sect was chasing the dao robe and caught Qian Jiaoxi. But it's originally something supposed to be smuggled to others, probably the money's already been paid, and for Qian Jiaoxi to intercept on the way would make Mo Zhu Mountain look unjust if it got out.
Moreover, Zheng Zetian has seen the Void Dao Robe, and it's actually no big deal. The base is his Undying Robe developed back then, using previously unseen special materials on the outside, which can almost completely shield Divine Sense search, probably similar to the corporation's cloaking technology. Moreover, this robe can react to malicious energy, absorbing Void Jade for self-repair, looks like the Giant added some of his own things.
