Maybe we're refering to different parts of the elbow. Looking at pics and vids of Dave Sevigny, it seems he keeps the pointy bits on the backs of his elbows pointed out to the sides. For iso, I'm thinking more like a volleyball bump position, with the pointy bit of the elbow rotated down or down and in forcefully, though I'm not really thinking about any particular way of organizing your feet and hands, but rather what to do with your arms and legs after you take your stance, whether it's Weaver or iso or the C.A.R. sillyness.
And I'm not saying it's the best posture for shooting, just that if you want to involve the upper body muscles, this might be a better way to do it than squeezing your hands together.