This is a very interesting use case. I would think that the patch catalog for Windows Server 2008 should show the patches for the HPC as well. And I dont have a HPC VM or any box to test with either.
My suggestion with this would be to open a ticket with BMC Support. They can test this in house and if needed, raise an RFE too. They might be able to give you a workaround too till this is supported by BL.
Let us know what you do finally.