Fear of getting hatred from Nintendo. In theory, they wouldn’t be able to know whether you are using anything pirated or not, but they are in no way doing piracy, and want to make Lawyers at Nintendo clear, that this is not just that. It’s only a third-party project to re-implement custom Nintendo Network servers to keep those console network features alive.
In general, it’s the same thing here in the Homebrew scene generally. While Homebrew generally profits for the piracy scene, the piracy scene doesn’t profit most of the time to the Homebrew scene, and in fact, kind of do the opposite (For example, Homebrew was more genuinely allowed, like PS1 Net Yaroze, which allowed Homebrew, but didn’t help the piracy scene in any way)
tl;dr : Associating yourself, to even slightly allow pirates on your project, just makes you extremely more likely to have problems with the law.