The speaker basically says OSDEV ignores the reality of modern computers. There are multiple binary blob operating systems with direct memory access running on a modern computer. OS researchers live in a linux bubble ignoring this. While this is true, I don't see how this is a technical problem for engineers to solve. This is a cultural/political/economic/moral problem.
Companies want to keep their stuff secret and governments want to be able to put backdoors into computers. How can an operating system software verify that the hardware is doing only what the operating system is telling it and nothing else if the operating system cannot verify the circuit layout of the computer? How can software verify the circuit layout? Afaik the only way to do this is look at the chip(s) through a microscope which is out of the scope of OSDEV.
I feel like this speaker has gotten me all riled up about nothing.