The Wikimedia Foundation per se doesn't have incentive or a goal to rebuild MediaWiki as something in which real security is a design goal right now. Which is somewhat unfortunate, as some commercial and organizational users could use that. The CIA did, but we didn't get the code.
I think you are confused on what Intellipedia's classification system does. Though the classification system they have is nice, it would be really easy to replicate (and probably in a slightly better way). It isn't page level ACLs, or anything like that.
Respectfully,
Ryan Lane