The UCI doesn't sell the TdF brand, ASO does... but you are kind of missing the point, the credibility of the sport has already been stretched to breaking point by the actions of the dopers getting caught... which is why the UCI doesn't want them caught (see the current battles between UCI vs WADA and ADFL)
German tv pulled out after Ullrich and Zabel, the French are losing interest too.
Armstrong has become a liability for the sport.
Why is Armstrong a liability? This always assumes that he has/does cheat.
Under these circumstances, anyone in the peloton who has tested negative, but performed well (Cancellara?) is also a liability.
You have to accept that the testing regime has constraints, but that it does detect people cheating. Therefore it does work.
Just because it doesn't give you a positive result for the person you want it to find positive is not a bad thing it just means that as a sporting rule it's working.
That person has either found a way around the testing regime, or they're not actually cheating.
Given the range of testing techniques applied and the period that they've been running you'd have to argue that someone who can keep ahead for years and years and years is either employing some pretty smart chemists to test himself constantly to make sure what he does is undetectable, or more worryingly, getting someone else to take stuff and then see if it can be detected, or they're simply not cheating.
Apply Occam's razor to that and the easier conclusion is that on the balance of probabilities either there's a huge hole in the way testing is carried out, or...