It can cynically be seen as keeping a cron job to run the GC on macOS (and non NixOS in general) as an enterprise feature by virtue of the stock packaging not shipping such a thing. That’s my understanding of it at least, a cron job with nice management.
Personally I would love if more energy would be put into the default UX of nix but at the moment the shell script installer reigns supreme in a way that looks exceptionally bad for the project, when the better packaging is developed by the employer of the project lead and sold as an enterprise feature.
These things do cost a lot of money to develop, and suck to test (and indeed it’s not like the Lix installer isn’t undermaintained either!), so I’m not saying it’s not reasonable to sell some packaging, just, it looks bad for the project lead to be employed doing so while the default packaging is as poor as it is.