That's the joke.
The title doesn't say that employee was fired to refer to that "joke". It says it because it's more clickbaity this way.
> The manager of this component replied, completely truthfully, “the individual responsible for this regrettable act is no longer with the company.”
Doesn't really sound like inadvertent or convenient HR/PR team handling, 'manager of this component'. How big would MS have been at the time (Windows 3.1, early 90s) anyway?
Sounds very much to me like they thought it was hilarious, and were thrilled to be able to say they were no longer there on a technicality!