I think Erik is pointing out that all other things being equal, transitioning from one target to the next within the FOV of the optic will be faster than having to locate the next target outside the optic and then acquiring it in the optic after transitioning.
The flaw I see here is that all other things are not equal.
When you look at where the optics are located on the two rifles in Erik's article, the one with the optic mounted forward leaves room to open the caps down, the second rifle has them in a flip up orientation. Most initial targets are going to be acquired from a low ready position. Flipping the caps up gives you more visual clutter to work through as you bring the muzzle up. If you tried to deploy the BUIS on the 2nd rifle with the caps flipped down, the rear cap would be in the way.
With the zero magnification optics, I think working too close to them reduces your peripheral vision. Situational awareness is critical to survival. You may be able to transition from one forward target to the next faster if you're working within the FOV, but what about a threat that's just outside your FOV that you didn't see?
The more things I have close to my eye that obscure
my FOV downrange, the more likely I am to miss something important.
A lot of high speed handgun shooters are moving away from large blocky rear target sights to ones with shaved down ears that occlude less of the target. They find it faster to transition from one target to the next with less metal to sight through. Running your optic as far to the rear as possible runs counter to that.
Speed within the sight to me is less critical than speed and FOV outside the sight. It's a big world out there and you can't get all of it inside the ring at one time.
