He didn’t trust Bae though. And he promised Bae that he would try to get rid of his power. And he was too afraid when it came down to it. And he also just let go of Bae’s hand. It is his fault even if i understand that he was afraid. I still think he made a mistake and it is his fault. And i still don’t see Rumpel as any sort of ethical being. He feels no responsibility towards other people at all only towards Bae and his desire to find Bae. That is all he cares about and is willing to do whatever to get that.