Looking carefully at the thread in question, we can see it was made by
Gramac Presents in 2021, and is in the Deleted Threads category. The thread was not locked when it was deleted, and Wikidot unfortunately allows posting in deleted threads by default. (I have since locked it.)
As such I believe that they stumbled onto the unlocked thread, unaware that it was deleted for racism, and posted in it. Because only mods+ can delete forum posts, users cannot self-delete posts and so when we saw that their post was the first one, we assumed they had also created the thread.
Therefore this ban was in error, and should be rescinded. I vote for allowing the user back on the site with an apology on behalf of the Disciplinary Team. The user should also be gently advised to not post in deleted threads, and be informed of the racist nature of the deleted thread, if not already. I also think we should recommend that they edit out their post in the thread.