I think Issue #89 wasn't fully addressed. Emacs still doesn't load a bare-bones config file for vimgolf. I think a current solution would be using a terminal command:
emacs -q --init.el
This would make emacs load up without the .emacs file, and init.el would be a custom init file specific to vimgolf. Then there's also the question of which modifications should be included in the default init file.
You're right in terms of implementation. At that point, we would offload the launching of emacs to the vimgolf script and maybe have some sort of --editor flag.
However, I would not support such a style of playing vimgolf in emacs, as I don't see the value in learning just vanilla Emacs when its whole purpose is to be a Lisp Machine that you can bend to your will. Most emacs users I know wouldn't even play something like this if they knew it required them to launch a fresh instance of emacs.
So I think for now, Vimgolf will remain a solo game for emacs users (at least once we get the mode working again…).
Happy to hear your thoughts though.