Well, I would expect policing to be stringent. Feelings are strong, and ENWorld has, in my entire recollection, been a place where civility has been enforced. That said:
If we have to use the banhammer more than a couple of times, you can expect that the topic will be restricted again.
This just sounds like an invitation for people to "act up." As others have suggested, I think the important thing is for people to receive the usual warnings, early and consistenty, for uncivil behavior. I think punishing the topic itself is counterproductive to the idea of a forum.
While I can see an argument for extending the ban another month, I have a hard time imagining it going longer than that. There is only much you can say without broaching the forbidden subject: some people prefer one edition over another, for reasons intellectual, social, and emotional. It is relevant not only to discussions about differences between editions, but a variety of other topics where these differences are relevant.
"You are stupid for liking X" is already against the rules, with or without a ban. Because it's already against the rules to say someone is stupid. But I don't think someone would be moderated for saying 3e multiclassing works better than AD&D's multiclassing, and so I wonder what purpose is served by forbidding someone from making an evaluative comparison between 3e and 4e's mutliclassing systems. At least, as I understand the ban, that would be forbidden because it would inspire someone to defend one game and criticize the other. But it's a worthy topic.