Maybe he’s recognized something brilliant. Management doesn’t know that the program he wrote was just a reimplementation of the Unix “cut” and “paste” commands, so he might as well get rewarded for their ignorance.
And to be fair, if folks didn’t get paid for reinventing basic Unix utilities with extra steps, the economy would probably collapse.
That's still probably the wrong way to do it, but 10 minutes for a 20k line file? That seems like poor engineering in the most basic sense.