The demon clan has been considered the greatest enemy to the humans. Any human beings that colluded demon clan don't get w good ending and this why the experts beyond the heaven mandate had to come out.
It was just that they where hesitant, for good reason. Once they made a move it would be necessary to silence everyone but among the millions of people in the city, who could tell the people behind some of them.
Being at their level, it is important to consider a lot of things clearly. Once their actions offend someone they shouldn't, it would be difficult to preserve their lives let alone their factions or clans.
The demon clan and the humans have always been fighting since ancient times, and their enemity can be said to be never ending.
