If he has caused that much of a problem, then just move on. Block him, stop mentioning him by name, and forget about it. For the open source community, he no longer exists.
I mean I feel like changing the domain name is less of a problem than the one all of the 4000 people named Andrew Lee who are not that guy now have. It's a lot harder to change a legal name. So they will have to live with his bad reputation potentially rubbing off on them. But luckily online most people use aliases so that should mitigate it somewhat.
Libera.chat is a more modern name anyway.