I think we all have the capacity to make wrong decisions when under stressful situations especially when you can feel the power of dark magic and have that power readily available. Do I feel that Bae would normally make this decision? Absolutely not, but he is in a situation where he desperately wants his dad to be seen as a hero and not be the town monster. He has been picked on a bullied and now here is someone else who says they are a “hero” who has killed several people and is going to blame it on his father. I don’t think this has anything to do with leaving towns it has to do with a teenage boy who in a moment has too much power in his hand and makes a wrong decision. His father sees this and understands that once Bae felt the power of the dagger it is addicting so he does the only thing he can think of to prevent his son from darkening his heart he makes him forget the power of the dagger.