I was unaware of this limitation in SBUU (I also rarely use it), but it seems as though it may have also blocked the Broadcom drivers that should be native to Server 2012 (meaning the Broadcom drivers are built into Windows and not available - or necessary - as a separate download.  I would try the install directly from the 2012 media, bypassing the use of SBUU to see if the drivers are installed properly then.  
I installed Windows Server 2012 Foundation on a recently purchased PowerEdge T110 II using the installation media that came with the server. There were two disks, one for the pre-OS environment prior to install and one with the Windows installation media.  Everything seemed fine, except the network card does not function. I attempted to install the OS Driver Pack, Version 7.2.0.5, A00 but it requires lifecycle controller. I tried the various network drivers on the support page, and they say no is network card is present. My assumption is that I have done something fundamentally wrong with the installation rather than Dell not providing the correct drivers. Did I miss some crucial step in the pre-install stage? In the documentation there is the following update information. I do not know if I missed some step or there is something missing from the support page.
Network card not detectable in Windows Server 2012 Foundation on PowerEdge T110 
II