from the book: "If your host hardware is using UEFI, then the 'make defconfig' above should automatically add in some EFI-related kernel options."
The book refers to a separate text document for more info on UEFI, including the requirement of an EFI partition on a GPT formatted disk. Dated 2017. (http://www.linuxfromscratch.org/hints/downloads/files/lfs-ue...)
At a minimum, disk layouts are drastically different in UEFI and BIOS.
LFS is so woefully out of date that it isn't even funny.