He didn't really.. he actually said that he doesn't see any science to support it, but then immediately afterwards admitted that nutrients are stored in vacuoles within the plant and that feeding only water at the end could help to deplete those stored nutrients.
I like to follow actual science as much as anyone but I will never feed a plant right to the end ever again. Done it several times because I kept hearing it makes no difference and science has proven it. Bullshit. I ruined 3 crops at least trying to disprove myself by feeding low dose nutes right to the end. Ended up with pounds of weed that wouldn't burn properly in a joint. Fine if you're a bong or pipe smoker. Useless garbage for folks like me that burn joints in slow burning papers and don't want it to burn out every other toke.
I want to deplete the stored nutrients from the plant at the end, and the only way in my mind to do that is with a week or so of plain water feedings to first deplete what's in the media, and ultimately deplete what is stored within the plant. In fact I'm even going back to the idea that utilizing an isotonic solution at the end to properly remove stored nutrients from plant vacuoles is the ultimate path to a clean and smooth burning end product.