Blue Profound Sect's aid would take at most a quarter of an hour before they reached and if he wasn't able to capture this young lass in time, bringing her away, then he would be seen by the Elder from Blue Profound Sect.
Based on his current ability, how would he dare to go up against the Number One Sacred Land's top rated practitioner?
Of course, he could also choose to turn around and escape right now, letting this young lass go. But earlier he had already exposed the fact that he was a member of the Leng family. Not only had he not caught her, he had also exposed the family's secret and if the clan leader were to find out about this, he would not be able to get around this easily!
Moreover speaking, this young lass used dozens of flying daggers causing him to become ashen faced so if he didn't teach her a lesson, just letting her go so easily, he was really unresigned over this!