I just do not believe this story. Nobody in the right mind will fire key software engineer 48 hours after system goes live. This is where all the bugs/problems show up and you need all hands on deck to fix them. Six months after launch when all problems are solved - absolutely, you can fire engineer. 48 hours after launch? absolutely not.
I think you significantly underestimate the lack of empathy and (lack of) concern for workers that this kind of management has
You need one or two more release to iron out the bugs, right?
...and this is a trading platform. The market changes, you need program changes for unforseen market changes.