In this negotiation scene, Ed tries to justify his inaction by throwing every obstacle he’s ever overcome at Erin, hoping this absolves him of having to do the right thing. 

This is something to note when writing dialogue: When we know we’re wrong or feel guilt, we will talk ad nauseam trying to prove our correctness or innocence. Notice that Erin, who in this scene has actual conviction and a backbone, doesn’t have to say much. She doesn’t have to convince herself that fighting for the people who have been poisoned is the right thing to do.