You may be taking the argument too far in the other direction. There are various sorts of bad behavior. Someone cutting ahead of me in traffic is being rude. But it would not outweigh everything good they may ever do in their life. For all I know, they are rushing to be there in time for their child's recital, to bring pies to a charitable bake sale, or anything else.
Some bad can never be undone. But that does not mean that people should not try to do better, if their conscience comes around. If there is no redemption, no reason to try to do something better, then the world may become a worse place.
Overall, I would say the two do not undo each other. The bad is no less bad for the good. But so too is the good no less good for the bad.