OK, but a mirror only exists to share an exact (hopefully up-to-date) copy of the repo. So we are just moving the goalpost from the moment you create the fork to the moment you edit it. Did that really change anything? I don't think so.
You can Zeno's-paradox-away the distinction between a bathtub and a kitchen sink, but that doesn't make them the same thing.
This sort of argument change how people understand words, and it also doesn't change how lawyers interpret laws nearly as often as people think. It's still fun, though!