Khelfin had to admitt to himself that Aro's speech did not leave him untouched. In a way, he could really understand what he was saying and it were the first deep emotions he felt after losing everyone he loved. When Sabrina jumped right in to Aro's plan with an innocent enthousiasm after only just meeting him, Khelfin realized these people where the closest thing to friends now. 

"Fine, I will join your stupid crusade. Without me, you'd get eaten by a Tyranitar anyway."