Allows you to mark Reputation Headers as "Inactive", when you normally cannot. Reputations such as "Horde Expedition" and "The Anglers", where the reputation is also a Header.
If you mark the Header as "Inactive" but its children aren't "Inactive", then the children will just become under the parent category. Eg: If "The Tillers" is Inactive, but "Chee Chee" isn't, then "Chee Chee" will become listed under "Mists of Pandaria".
Known issue in 10.0: Has some unavoidable issues if you have almost all of your reputations marked inactive.