It looks like he is guilty. I do not think this detracts much from his achievements though. Bjarne Riis has admitted to doping to win the Tour de France, Floyd Landis (the person I thought least likely to cheat) was caught taking steroids. Most of the 1984 US cycling team used blood doping which was not illegal yet since there was no test for it but widely considered cheating. Eddy Merckx was caught using amphetamines and famously quiped, "You don't win the Tour de France on bread and water" implying that it isn't possible to win without doping, Bernard Thevenet admitting taking steroids. Many years there was no test for the drug EPO and it was largely ignored until riders took so much EPO and increased their red blood cell count so much that their blood literally got too thick to pump leading to heart attacks. I think he is guilty but considering the pressure on professionals to succeed and the nature of the events it is entirely understandable why athletes do this. I hope some day cycling is clean and riders will be able to race clean without being at a disadvantage.
He is guilty. I think he was doing this once he started winning, but guilty for sure.