This would need to be handled within MailChimp (or other campaign tool) itself since the sync will have already occurred. We don't have a deep level integration w/ MailChimp as of yet (and I'm not sure we should focus just on MailChimp).

That being said, I agree it makes sense to have an "Inactive / archive" type flag for curlers. Not sure yet what filters would use it, but I'm going to add the flag for starters and then we'll see how we want to use it.