Earlier quoted context omitted.
IMHO the original choice of the path seems incredibly ill-advised and the main burden lies with the original developers. sometimes old errors and mistakes come back and bite
What is special about /nix that would make it better suited elsewhere? Aesthetic? Clutter? I don't think there are any technical reasons why the root of the filesystem is important. The /nix folder is just another folder with some ACLs/Permissions (however OSX works, idk)
So while /nix is no problem from the filesystem driver, it is completely flaunting established Unix norms.