Imagine a patient dies during surgery because the surgeon didn't wash their hands. Would you give the surgeon a second chance or just fire the person and revoke his license for not following basic hygiene procedures?

Likewise, a programmer that doesn't provide deliverables that are maintainable is also disservicing the company, and society as a whole.

There's a difference between a legitimate error and negligence. In this case, the problem looks like negligence and was easily avoidable.