It seems to me that the proper response is to:

• Remove the offending material from the nodes.
• Remove all XP gained from the posts from the posters.
• Revoke node approval priveleges for a period of time (if removing the XP does not do so).

I don't see the point of a suspension or ban; it's really not worth the effort to devise a system that ties accounts to user identities so strongly that someone cannot sign up again for a new account and start over.