Let's say you are hallucinating "two distinct meanings of fork". Unless you are referring to tableware, a fork is a fork, it's any distribution of a software, based on the software in question. The fact that most forks on GitHub serve only operational purpose, nobody actively maintains them and nobody normally uses them instead of the parent project, doesn't change what they are: a distributions for (potentially, and unless PR is accepted, actually) distinct software projects, based on a project they are forked from. You are just so used to the button and the process, you lost track of what the label on that button actually means, why it's called "a fork". And the answer is, well, because it's a fork. In no way it is different from starting a MariaDB project. As soon as you press that button, you are distributing your own software, based on that parent software. If the parent project disappears, or moves on, or never accepts your PR, which somebody really likes, other people can (and probably will) use your fork in a way that isn't any different than, well, any larger and "more obvious" fork.

So, essentially, winamp license means nothing. They already forfeited their right to deny you forking by posting it on GitHub.