Believe that is called interference, not blotting. Blotting means something similar to what heavy atmospheric moisture does to sunlight. Unless they are insinuating that their will be more plasma gasses and the gasses themselves can blot out the sun similar to what happens in space nebulae. And they are incorrect to assume that putting pressure on our atmosphere will not affect climate change. New studies have shown that our atmosphere expands during low solar activity. Basically due to pressures (energy). And your linked study states that our atmosphere can drastically shrink with solar winds 10 to 100 times greater then present. That also increases pressure.