But people on NixOS may use his software...if not in nixpkgs then someone will just maintain their own overlay that many people use. It's impossible to stop - if there's demand by NixOS users for this software, they're gonna package it up and patch it in order to keep Nix Nix..

Hell, I could go make that overlay right now and link it in a nixpkgs issue for discoverability. What's this frenk person gonna do? Cut me an issue saying "pls delete this code from the internet"? Hah!

Why would users report to his project when installing Home Assistant? That's not usually how it works and Home Assistant has a lot of other dependencies.

His library was written specifically for Home Assistant and it's an internal dependency that no one usually sees. It's a 300 lines wrapper for Ambee API.