You can’t get the full story from just one article on the site because brr consistently use way, way less than the manufacturer’s recommended sealant to test tubeless tires. You have to cross reference with data they show in the sealant comparison article.
For the really sharp eyed you’ll notice they sneak in tubeless rolling resistance taken from a setup with very, very little sealant in the tire.
Am I going to have to post the annotated graphic again? 