The old Something Awful forums did something similar. If someone posted something that was unacceptable, the comment would generally stay and the comment would

The old Something Awful forums did something similar. If someone posted something that was unacceptable, the comment would generally stay and the comment would get a tag saying “the user was banned for this post”. They also had a moderation history so you could go back and see mod comments on why they gave bans/probations.