Hi Clint,
According to Microsoft page update KB2687324 has been added to MS12-043 after this bulletin was published:
http://technet.microsoft.com/en-us/security/Bulletin/MS12-043
"V2.0 (August 14, 2012): Bulletin rereleased to offer the security updates for Microsoft XML Core Services 5.0 that were unavailable at the time of initial release. Customers running Microsoft XML Core Services 5.0 should apply the KB2687324, KB2596856, or KB2596679 update to be protected from the vulnerability described in this bulletin. Customers who have already successfully installed the updates originally offered on July 10, 2012 for Microsoft XML Core Services 3.0, Microsoft XML Core Services 4.0, and Microsoft XML Core Services 6.0 do not need to take any action. See the Update FAQ for details."
Most probably you have created policy containing MS12-043 before release of V2.0 (August 14, 2012) and checkbox 'Automatically revise Software Update policies after importing patch data' is not checked in your PM Import settings.
To make update KB2687324 available for distributing you have the following options:
1. Navigate to Import Patch Data for Windows page and enabled checkboxes 'Automatically revise Software Update policies after importing patch data' and 'Enable distribution of newly added Software Updates'. With these settings all newly added updates will be automatically staged and enabled in existing policies during next PM Import task.
2. Create new policy with MS12-043 bulletin. New policy will be created with all updates included to MS12-043.
Hope this helps,
Roman