Intel does not open source their BIOS. Further, their BIOS is protected against tampering.
Visual BIOS is a program to present and support the modification of BIOS configuration parameters. Other than that, it does not have anything to do with BIOS POST processing or hardware initialization.
Intel Customer Support will need to pass on this request to the development team for consideration.
Can someone from Intel Customer Support relay this as a feature request to the right team. If it helps, please talk to Jarkko Sakkinen <firstname.lastname@example.org> who is an Intel Engineer who wrote the Linux Kernel driver for SGX. He can probably explain the significance of this feature far better than I can.