Brooo, yeah a shit reason, and all this just felt force to give a redemption. In the end they need to live with that they put a hex on him, that could/did kill him. He such a kind hearted man like they said then he would still use his magic even if meant slicing his life off.
I know alot of manga are trying make the mc not kill old friends and be strong and really nice, but they make them way to soft. You would think a like 40 year old man would know that people are bad (not animals or monsters), and are not good people to friends and familys also. Like they need to...