Nix run issue with apps output

In the following flake, can someone explain why the runScript output is actually necessary? I wrote it while using a similar flake as inspiration.

  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

  outputs = { self, nixpkgs }:
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};
      name = "hello";
    with pkgs;
      packages.${system}.default = stdenv.mkDerivation rec {
        inherit name;
        src = ./src;
        buildInputs = [ cc65 vice ];

        buildPhase = ''
          ${cc65}/bin/cl65 -C c64-asm.cfg -u __EXEHDR__ -o ${name}.prg ${name}.s
          ${vice}/bin/c1541 -format diskname,id d64 ${name}.d64 -attach ${name}.d64 -write ${name}.prg ${name}

        installPhase = ''
          mkdir -p $out/bin
          cp ${name}.d64 $out/bin

      runScript = writeScript "runit" ''
        #!/usr/bin/env sh
        ${vice}/bin/x64sc ${self.packages.${system}.default}/bin/${name}.d64

      apps.${system}.default = {
        type = "app";
        # program = "${vice}/bin/x64sc ${self.packages.${system}.default}/bin/hello.d64";
        program = "${self.runScript}";

If I instead try to use nix run with the commented out program value, I get the error saying

error: unable to execute ‘/nix/store/q0in8853fh4ghr57bxxz6faa6bvwydfy-vice-3.7.1/bin/x64sc /nix/store/gjrdjzn264lpaxssk1c5grag5n91y09y-hello/bin/hello.d64’: No such file or directory

The paths specified in the error message do exist and that exact string does in fact launch the binary. Is the program value simply unable to handle arguments, or what?

Yes. The error is somewhat broken, though, maybe this should be an issue upstream.

It would also be lovely to have more flexibility here, a type that does accept args and one that feeds things to writeScript would save a lot of typing.