Because you're pushing the code to GitHub, so they need to enumerate their rights in terms of what they can do with it once you push it there. But if you publis

Because you're pushing the code to GitHub, so they need to enumerate their rights in terms of what they can do with it once you push it there. But if you publish your code to PyPi, the relevant ToS is the PyPi ToS, which has no such clause forbidding either PyPi or others from using the code how they'd like to (and as mentioned by other comments in this thread, the ToS actually explicitly grants others the right to republish the code).