Then it was, clearly, negligent of him to give it to this person. He gave a stranger the power to do things in his name.
He doesn't have to maintain the project forever - it seems like a much easier solution is: don't give away a project with your name on it to someone you don't know. Instead, encourage them to fork and release a new version under their own name. This is a surefire way to never have an exploit spread to thousands of people with your name on it.