You've shown that Greeks had connection and knew about black people but that wasn't disputed... The claim was that there was "plenty" of black people in Ancient Greece. Connections to people being in Ancient Greece aren't the same...
I'm not sure why you are taking the burden of proving someone else's claim but you're now trying to spin that burden to me to prove it the other wat around. That's just silly.
Why not trust the other guy to make their case?