Permanent solution could be an admin/mods made account (or just them) that is only for this kind of topics (pinned topic). This thread can be edited by mods as well so it will be easy to edit it when it becomes outdated just need a reminder.
Creating special account just for pinned posts is kinda over complicating the issue and it would be more elegant if they just did it by themselves on their own main accounts. After all, how often mods get tagged for scams?
May be I messed up my memory but as far as I remember the plagiarism thing happened a long time ago and after discovering it we also passed long years. When Lauda asked for banning herself, at that time there were nothing existed, she was doing well and the good bye thread came just suddenly. Again I may messed up my memory, after all I am ageing 🤣
Iirc plagiarized posts were made in 2015 and they were discovered in 2020 so yeah I think you are right. And then few months after the discovery, Lauda decided to leave the forum . Since he didn't get any sort of ban in the meantime I am not so sure that was the main reason for leaving. Unless he felt kinda embarrassed with all that mess since he was very strict when other plagiarized and decided to leave.