How is Resha'im's Dibur an ambush of blood?
Rashi: They counsel to murder with their hands, or via false testimony.
Malbim: Dibur is speaking at length and clarifying the matters. Resha'im do so to carry out their intent, to kill. They speak Leshon ha'Ra and Rechilus to destroy their colleagues.
How does Pi Yesharim save them?
Rashi: When they hear [Resha'im's] counsel, they save the [intended] victims. They reveal the counsel, or if [the Resha'im] are witness, they are Mezim them.
R. Yonah: When Resha'im bring false witnesses against people, Yesharim defend the accused. They are Chachmei Lev, who recognize and love the straight path. Since they have the ability to save via their Chachmah, they are obligated to do so.
Malbim: Yesharim have the laws of Chachmah planted in their hearts via nature. They go beyond the letter of the law - the opposite of an ambush for blood.
Here it says that Pi Yesharim saves them. Above (11:6), it says "Tzidkas Yesharim Tatzilem"!
Malbim: There it teaches that through their virtue, they are saved from evils of nature and Hashgachah in which Bogedim are trapped; Yesharim's merits save them. Here discusses evils that people chose to do. Their mouth saves them via the laws of Chachmah.
