Using poison when one couldn't win was a despicable thing in most people's eyes. This was the main reason why Jade Face Poison King had infuriated numerous people back in the day.
However, this kind of thing had no psychological effect on Qin Mu. In his eyes, poisoning someone when one couldn't defeat them was something that was right and proper. Poisoning the opponent was also an ability. His logic went along the lines of 'if I can't fight you yet you still come to beat me, poisoning you is a fitting answer'.
For example, what they faced was not a fair fight from the start. Dragon Rearing Sovereign was a god of High Heavens that was high above, so the clone that was formed by his fresh blood also had extremely high abilities. Even strong practitioners of Celestial Being Realm wouldn't be a match for it, let alone Qin Mu and his companions.
The opponent was a god, so poisoning him was a normal fight back method.
