It’s their choice. I’m sure they also had this in the works as well, but it eventually didn’t work out (why pay another dev when we can have the ones already working for us do this as a side project… they basically just have to clone the repo and change a few things, that’s it).

As I said, he can sue for not mentioning the original project, but not much more… maybe he’ll think a bit more about what license to choose when publishing big projects like this publically.