There was only one and is only one solution to this problem. Everyone needs to stop playing against these sort of people. You see him? Turn around and go away. If they can't find anyone they will vanish. They live from attention. Never forget Warcraft 3 and what happen there. A bunch of people started hacking to post their egos and jerk off to their stats/%/profiles. It destroyed the whole ladder and community back then.
We called these people always "kleiner Penis". Not because of there possible small genitals rather their small egos and lack of self-consciousness.
Search aoe2insights for the opponent (in this case _gg_) and go to their match history.
From there you can click on the blank name profile and see the numbers at the end.
Copy those numbers and paste them at the end of an aoe2.net profile link and it will be the correct player.