Got this done easy enough in the end, just took a bit of thought as to the best way to do it.
So, I moved all the topics to a new sub forum, Security Updates, and the simply added this to the SQL that generates the latest posts. (64 being the id of the Security Updates sub forum)
WHERE .... AND `forumid` != 64;
As an additional step I restricted this sub forum to registered users, this has the effect of removing it from the RSS feed and prevents google from crawling it and seeing it as duplicate content.
Another benefit of this strategy over just stopping posts from the ArticleBot user appearing, as first mentioned, is that if any new security feeds are added to this sub forum they will also be treated like this too automatically.