“You told me you could prove it but that's an assertion and not a proof. I don't accept your assertion, which is unproven. Do you actually know what a proof is?”
it’s asserted because it’s already known to be true. That’s how a math proof works.
I even gave the exact formulas for the mirror moves in my original proof
What is important to note is that black does not HAVE to play the mirror move, rather that they COULD choose to do that. If white decides to lose 2 tempo, black does not have to Match that.