He’s an example of a trope I’m not found of. I don’t know if there’s already a name for it, but it’s the trope of the villain turned hero at the last minute but dies by the end so that the story can give them both redemption and punishment without having to have our heroes deal with the messy matter of bringing them to justice when the story ends. It’s romantic to see the villain have a change of heart and do the right thing in the end. Less so watching them get taken away in handcuffs for their crimes after the fact because one good deed doesn’t erase what they did.