My production environment contains a Server 2012 R2 Hyper-V Core installation.  There is then a gen 2 VM running Server 2012 R2 Standard edition which has WDS installed.  Using this WDS server, I have been able to get a second gen 2 VM, running on the same hyper-v server to pxe boot a 64bit Windows PE5 wim.  

As server 2012 is supposed to support UEFI booting of a 32bit PE5 image, I uploaded one of those as well.  However, it will not send the 32bit PE5 image to the Gen 2 VM.  

Forums mention that the vendor hardware has to support this.  Does Microsoft Hyper-V 2012 R2 not support uefi booting of a 32bit PE image from their own servers?

Yes, I can do a gen 1 machine and legacy pxe boot from the 32bit PE image.  Even if legacy was an option, the legacy network adapter is only 100Mbps and takes much longer to image.  

The limitation is not on the server side here, it's on the client side. Hyper-V guests are 64-bit by design and thus must boot into a 64-bit OS when UEFI is used -- this is by design and definition of UEFI. To PXE boot a system using UEFI into a 32-bit OS, the machine must truly be a 32-bit only system. Note that when I say OS, that means Windows or WinPE -- they are both OSes.