I can kind of understand what he says about adjusting the time from the BIOS settings, but most people doing anything with BIOS/EFI settings nowadays are techni

I can kind of understand what he says about adjusting the time from the BIOS settings, but most people doing anything with BIOS/EFI settings nowadays are technically involved enough that understanding UTC shouldn't be a dealbreaker. The dual-booting arguments are weird because if anything, dual-booting becomes potentially more complex with the RTC set to local time. Both operating systems might e.g. separately adjust the local-time RTC for daylight savings since they can't know the other OS has already done that. If he had just said "well, this made sense with the positions from which Microsoft was doing things back in the time and we never got around to changing it", that'd actually make more sense than making kind of plausible but almost certainly irrelevant arguments for still doing it the same way.