There is still a valuable lesson for the developer here though - double check everything, and don't screw up. Over the course of a programming career, there will be times when you're operating directly on a production environment, and one misstep can spell disaster - meaning you need to follow plans and instructions precisely.
Setting up your development environment on your first day shouldn't be one of those times, but those times do exist. Over the course of a job or career at a stable company, it's generally not the "rockstar" developers and risk-takers that ahead, it's the slow and steady people that take the extra time and never mess up.
Although firing this guy seems really harsh, especially as he had just moved and everything, the thought process of the company was probably not so much that he messed up the database that day, but that they'd never be able to trust him with actual production work down the line.