What isn't? The article is just saying these things are good for you.
It’s the concept of ‘unclog’. Atherosclerosis is a complex process that involves many things, including inflammation, cellular and extracellular accumulation of cholesterol (humans cannot metabolize/degrade cholesterol), fibrosis, calcification, proliferation of cells, etc. Clearly a good diet is an essential part of trying to avoid developing atherosclerosis, but reversing it once it is established is not in any way a simple process.