Understandable that hey got fired. I image there would have been a quite emotional response from the business when this happened, but that doesn't mean it was necessarily the most appropriate response.
--Unfortunately apparently those values were actually for the production database (why they are documented in the dev setup guide i have no idea).--
Someone else should have been fired if this is true.
No, it's inappropriate. When the process fails you don't fire the junior employee that showed you just how incompetent the organization is. You fix the problem.
Firing this guy does nothing, fixing the problem does, but requires those higher up to admit the mistake was theirs to begin with.
I should clarify, I don't think its appropriate, But I see why it happened. The business was panicking. His firing was kinda on the cards. Probably a blessing in disguise for this guy.
--Unfortunately apparently those values were actually for the production database (why they are documented in the dev setup guide i have no idea).--
Someone else should have been fired if this is true.