If we are trying to draw comparison between Armstrong and political wrongdoing, it seems somewhat straightforward: in the case of Armstrong, it's much more black and white than in the case of bankers and politicians. He admitted wrongdoing and put himself on the cross for the nation. Contrasted with the case of bankers and politicians, who dwell in the eternal grey area, never once owning up to their misdeeds, the comparative black-and-white of Armstrong's admittance makes it much easier to have a simple and straightforward moral enmity.
Humanity likes to deal in black and white situations, and Armstrong's is much more black and white than anyone else. If he had not admitted his wrongs the vitriol would not be as strong and the impact would not have been as large.
As much of an asshole as Armstrong is purported to be, because he actually stood up and spoke out, he deserves so much more respect than those who have done so much worse and fade into the grey wall of evil in obscurity.
If we are to consider our society to be based on some sort of ethics, it is clearly a wrong that has been accomplished on Armstrong's part and he definitely deserved at least a good portion of what happened to him. But to see a man who really did not much more than make a fool out of a beloved sport crucified more than those who have actually contributed to the financial ruin of millions of Americans by facilitating the financial crisis, for instance, is nothing short of depressing.
And do not interpret my comment the wrong way: I feel no sympathy for Armstrong. The absolute worst case scenario for him touched on in the article is that he loses the lawsuit and has to pay away everything but keeps his apparently untouchable 8 million dollar home in Austin, which he might be forced to sell and then live a comfortably upper middle class lifestyle that would still be better than most of the better off earners here on HN.