It would seem that McAfee SiteAdvisor has developed a bit of a hiccup with it's ratings system, or, perhaps their crawler has a bug in it.
These are obvious mistakes in the system somewhere. The SiteAdvisor group has been made aware of these mistakes and are taking action to correct them. It just won't be as fast as we would like.
I am rated as an 'Experienced Reviewer' and as such, my comments carry a little bit of weight in the ratings of sites. If you're aware of a site which needs some corrective commentary, be they good sites flagged as bad or visa versa, let me know and I'll work my mojo magic on them.
UPDATE: SiteAdvisor is attempting to whitelist these types of security forums and correct the problem.