Yes they got paid for producing the work, yes they were jealous. Yes they reacted like most humans would.
But, that €20k did not cover the copyrights to the work. Just the creating of it. Regardless as to whether you think the original payment was really good. The copyright sits with the artist, not those that commission it, unless the artist signs it away. That didn't happen. That's Mojang's fault not the artist. And the fact they were trying to pressure the artist into doing that shows that that is the real issue.
This post is not about the money or the jealously. It is about the emotional journey the author went on, with their human emotions, and what they thought of as friends. And the different stages of said journey.
If I was more cynical about this piece I would suggest that releasing the poem under CC was easily the worse thing the author could have done from MS/Mojangs point of view. Clearly a decision was made by them that should a lawsuit come about they weren't worried. Releasing it as it has been side steps this completely, leaving the power with the author.
Ultimately though I enjoyed the story.