So Goblins and MinMax could open the passage. He didn't miss them. He was shooting them for being EVIL, by associating with Goblins (i.e. fighting each other). Forgath knew Kore can't be reasoned with.
Kore would kill Idle for either A) being EVIL due to being non-human B) for allowing herself to become non-human. Bumper would be killed for associating with Idle.