Hi Antony, and welcome to the VMware Communities!
A no-emulation El Torito entry with type 0xEF will be regarded as an EFI System Partition, in which case it's expected to describe a disc region containing a FAT filesystem with the ESP contents. See UEFI 2.3.1 Spec section 12.3.2.1, "ISO-9660 and El Torito".
An El Torito entry representing an emulated device will still be treated as a block and disk device, per UEFI Spec section 12.3.2 "Partition Discovery", which says: "The EFI firmware produces a logical EFI_BLOCK_IO_PROTOCOL device for: [...] each El Torito logical device volume; [...]".
As far as I can tell, any BLOCK_IO device with BlockIo->Media->RemovableMedia set to TRUE (as would be the case for a logical block device sourced from a CD/DVD), containing a supported filesystem, is expected to be a candidate for default boot per UEFI Spec section 3.3 "Boot Option Variables Default Boot Behavior" and Section 3.4.1.1 "Removable Media Boot Behavior", so we should attempt the default boot paths on any filesystems from El Torito "emulation" entries even though they're not EFI System Partition entries.
I'm not 100% certain of my interpretation of this, and I know we did make a few changes so that we were more liberal than the default implementation in seeking out a bootloader, so it's still quite possible that we may not be following the specification in this case... or perhaps it's your hardware that's broken! 
Please let me know how this fits in with your understanding and observations!
Cheers,
--
Darius