So basically your argument is that draw speed determines if you live or die and what you refer to as buried carry slows draw speed and hence will result in you being killed. Is that right?
As a general rule, the more concealed a gun is, the slower the draw. There are exceptions, but the rule is essentially correct.
In the image posted on the other site (your link), the gun rides hide. It is less concealed and should be a quicker draw.
However, the picture shows a sort of classic example of something else that can hamper a proper draw and would be, by your accounting, "risky business under stress."
That is some wadding of shirt all bunched up there around the pistol grip. No doubt the person in the image will have a fast draw and a firm grip, on the gun's grip and a wad of shirt and as the shooter goes to extend his arms to acquire a sight picture, that shirt may or may not yank from the grip. If it does yank free, it will unsettle the draw and slow it down. If it doesn't, it will really screw up the shot.
If you are going to wear shirts with IWB holsters as shown in the image, find a shirt that actually fits. Having a wadding of excess shirt bunched up like that around the gun is a postential distaster, especially when discussing the need for speed. If you can't afford properly fitting shirts, then learn proper shirt tucking such as a military tuck, but with folds positioned such that the excess material is NOT under the gun's grip. If the shirt is a close enough fit, you can tuck one sided, just on the opposide side from the gun, thereby keeping the material pulled tight under the gun.
Otherwise, you can go tell St. Peter and Jeff Cooper how brilliant your fast draw IWB holster worked, but how poorly you picked clothing that interfered with the draw.