Comment by arcfour

Citation for what? The existence of bootkits?

Petya/NotPetya, Alureon, Carberp/Rovnix, Gapz, LoJax (firmware rootkit!).

All of these attacks would be thwarted by SB (and in Petya's case, simply having UEFI enabled at all, since that was only for BIOS machines)