AJ is a professional company. If you read the other comments, which were posted after my comment, it's clear the developer made an agreement a freelance journalist, not AJ; which isn't even mentioned by the developer in the blog even though they're 100% aware of it. Given near the journalists or the developer have committed publicly to the terms of the agreement between them, I don't see the point in speculating what their agreement was; I do know on GitHub that the developer use the MIT license for some other code, which would have allowed the journalist to reuse the code where ever they wanted.
As for what to do, volumes of books are published on the topic. If the content was hosted in the US, the next step would be contact the ISP that's hosting the content.