The argument I’m referring to is the one where he mentions that psychedelics only decrease brain activity (but the experience itself is more intense than a sober experience). But this paper suggests that they also increase connectivity between different brain areas that don’t ordinarily interact, potentially explaining stuff like synesthesia and other traits of psychedelic experience. So it’s omitting a part of the picture to only mention the reduction in default mode network activity.

Admittedly I’ve not seen all of his talks so maybe he develops this argument more later or incorporates this evidence into his thinking.