He is a paid Home Assistant core developer. (Hired by the company the project's founder created to generate sustainable income for developing the project by offering optional value-add services).
This library was written specifically to be used in Home Assistant, as per project policy the code that interfaces with devices needs to live in a separate python package. So there is no real fame to be had from this particular package.
He surely sees this repackaging as a source of potential headaches. If the nix folks could convince him that the package would never contain modified code (no no untested/unsupportable modifications), and further that the home-assistant package in nix would always use exactly the version specified upstream (so no version mismatch concerns), he would likely be less opposed.
Unfortunately the latter is very much not true right now.
