The short answer is that this can’t be easily mitigated at the package index level, at least not without massive breaking chances to the Python packaging ecosystem: PyPI would have to ban all setup.py based source distributions.

Even then, that only pushes the problem down a layer: you’re still fundamentally installing third party code, which can do whatever it pleases. The problem then becomes one of static analysis, for which precision is the major limitation (in effect, just continuing the cat-and-mouse game.)