From here on out, this thread is the continuation of this thread posted elsewhere. This is a matter of site policy, and all staff members are welcome to join in the discussion.
The issue raised is this: a banned user wanted to participate in collaborative efforts with other users, and be credited for the work in the article (including critique threads).
I've addressed this already in the above thread, but I want to restate it here for the sake of simplicity. This is how I have interpreted our rules pertaining to bans.
Banned users are not allowed to contribute to the wiki. This includes posting in the forums, voting, commenting on articles, or authoring articles. However, we do not have jurisdiction to enforce behaviour outside of the wiki, and cannot control whether or not banned users are contributing anyway, and just not telling us about it.
To this end, any article posted that contains co-authored material written by a banned user is subject to summary deletion. Articles posted that contains co-authored material by a banned user and that do not identify that they are using another user's material are subject to summary deletion for plagiarism, and for containing material written by a banned user.
In simpler words, collaborative efforts with banned users is prohibited, and attempts to do so are subject to summary deletion.
Feel free to discuss.