When Lu Jin received Bai Qingyan's decree to gather evidence of the sins of the Imperial Family's clan, he guessed that Bai Qingyan aimed to weaken the vassal kings... and deliberately created a deceptive appearance to them, which is why he didn't act against the Jin Dynasty's Imperial Family clan.
Moreover... Lu Jin suspected that the rumors claiming Bai Qingyan refrained from targeting the Jin Dynasty's Imperial Family clan out of consideration for the Eldest Princess were spread by Bai Qingyan's orders.
