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 This thread can be edited by mods as well so it will be easy to edit it when it becomes outdated just need a reminder.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?
The creation of special account is to avoid of having negative feedback since it will only be used for such purpose since the main issue here is the account/s of having negative trusts/tag because mods even admins can be tagged, like who knows they are not inevitable from that