Did you read the article? They go into intricate detail about how having Rick on the team was a detriment to the project. I quote:
I dove into the source code. Rick was right: no-one could possibly understand what Rick had created. Except for Rick. It was a reflection of the workings of his own mind. Some of it was very clever, a lot of it was copy-pasta, it was all very idiosyncratic, and it was not at all documented.
I went to our CIO with the verdict. Only Rick would ever be able to maintain this product. Plus, every day that Rick worked on the project moved the delivery date back a week. Rick was destroying our product faster than he was creating it.
They didn’t fire Rick because of the rant. They fired him because he was destroying their project.