By focusing on the Tour, he would be giving and beating Froome in a not banned/tired/injured fight. He would solidify his status of number one against all comers, passing the torch only in retirement, which may be his existential goal for the year.
I don't think he needs anything extra to do that. He just needs to not be hurt/banned/injured.
Like so many riders who have been caught, what they got caught for is not their rocket fuel, so they have no need to change their rocket fuel. Contador probably only changed his doping program not to include clenbuterol, or is doing more research about labs' new testing accuracy and precision. (He was probably screening his blood before bagging it, but his own testing couldn't match that machinery that caught him.)