Super Cub. Thank you for politely asking the question. Let me explain...
"Isolated" is exactly the word I intended.
A hunting rifle is usually fired with the forward hand holding the rifle. The object of this particular exercise is to zero the rifle for hunting purposes. That is a little different than shooting the rifle off a rest and trying to shoot the best groups.
Accuracy comes from consistency. It does not much matter what happens to the rifle, as it reacts to what it is resting on (sand bag, bipod, log…) so long as the rifle can react the exactly same for each shot.
We could debate whether or not a rifle swill group better off a sandbag or a bipod. What we cannot debate is that the rifle would shoot to a different place, depending on whether or not it was bouncing off a sand bag or a bipod.
So, if Radar wants to zero the rifle for hunting, he should rest the rifle in a manner most consistent with how it will be shot in a hunting situation. My suggestion is to make the test as independent as possible of the rest used to steady the shot. The way I do this is to rest the back of my hand on something and to hold the rifle.