Because Destiny had rarely been active in the Lower City area before, and had been dormant for decades until recently reappearing to cause a major incident in the Upper City.
Furthermore, the Upper City Council has always strictly blocked information about Destiny, and Destiny himself has a benevolent style of "reunite families," leading many people to have vaguely heard of Destiny's madness and terror, but they know very little about what mysterious techniques and abilities he actually possesses.
Especially since the Deceitful Martial Six Techniques or some secret techniques like the Sight-Based Perception are ones that Destiny researched and developed during his dormant period.
Outsiders know even less about this.
Moreover, he has always been stationed inside the Hidden Sect in Zone 9, so it's quite normal not to know these things.
But his intuition told him that the enemies he encountered today must be involved with some dangerous secret or organization.
