This user, whom you refer to as "Geriatrix", is still behaving in similar ways under countless alt accounts. On average, he makes 1 smurf account every 5 days. Generally, a new alt account is born after he has an argument with somebody.
I have an entire folder full of chatlogs and screenshots of his transgressions against the TOS and other players. He becomes hysterical at random times. However, clearly you cannot do anything about him, because:
1. He knows how to bypass mutes and bans. He has spam posted links to videos teaching ban bypass on multiple occasions, in the public lobby and hosted games. The 0ad moderation techniques are ineffective against him.
2. Moderators wants to silence any arguments and dissent instead of solving them, because that's less work and keeps the image of 0ad good. In the minds of moderators, he is only verbally toxic and posed no technical threat so he can be royally ignored.
Fortunately, there are ways to deal with him:
1. It's very easy to identify his smurf accounts because he talks in a very particular way and plays certain cav strategies with Romans / Gauls.
2. Keep a blind eye to him, pretend you didn't know or care. He is calm 50%~80% of the time.
3. Always talk politely to him even if he insults you. If you can't deal with it anymore, ban.