It is a triple crank set. It only chain rubs slightly on the chain device on the larger rings within the cassette, which never get used on a 4X track. I might inclued spacers and remove some of the spockets on the cassette and run just 4 gears.
He's saying that the crankset that he's using on the bike in this pic was originally a triple. He took off the rings and is using a single DH ring. All XT cranks up until model year 2012 have come in a triple ring set up.