Your eye is still open under that flap though, no? I dabbled in Olympic pistol shooting back when I was doing across-the-course service rifle, and I was told to always keep both eyes open by the dude teaching me. Same for service rifle (and later palma). I always found that closing one of your eyes fucks up your focusing. If you don’t have the little flappy dealy, you just do your best to defocus/deprioritize the view out of your non-dominant eye. I actually went for quite a while without any sort of cover because it helped me avoid cross firing (which is probably more of an issue with across-the-course than with Olympic pistol).
You’re absolutely right about the lack of spectacles though. This guy is one hell of a marksman.
The unusual factor at the Olympic level is that he both chose not to wear a blinder and not to close his eye. This means he was getting visual input from both eyes, that as you noted he had to block out mentally.
When shooting is down to the millimeter, all of this is important. This is the exact opposite of practical shooting, where you want a large field of view, or potentially an occluded eye effect to aim in some cases. (Cover the front of a red dot and then aim with both eyes open for a test of occluded aiming. Your brain will overlay the dot from the shooting eye and the target from the weak side eye and you will be able to aim. It will not be down to the millimeter accurate however, which matters within the abstract environment of target shooting.)
