The guy has an extremely bad hip - so bad that he walks with a pronounced limp when tired. When he isn't, he's developed an odd kind of walk that sort of hides it.
He injured last year in a crash. The bone is deteriorating so rapidly that he'll have to have his hip replaced in the next few months. It's so bad that most doctors can't even imagine how he can bike.
Simply put, the guy needs steriods just to stand up - they didn't give him any performace edge. If anything, he had to battle a handicap that would have sidelined 99% of the field.
In my opinion, this is just a continuation of the Lance Armstrong thing - the French are so pissed at the American dominance of a sport named after their country that they will go to any lenghts to discredit any American that wins.