As some have already noted one significant element of the confession is the light it sheds retroactively on Armstrong's indignation about allegations that he was doping over the years. Public expression of indignation may be the single cheapest commodity on the internet or in mass media of any kind. It's easily dished out for any number of reasons. Some of those reasons may be legitimate but we live in a time and media space where the tone of outrage can be ratcheted up so high that the boy who cried wolf no longer deadens the possibility for fear when the wolf finally arrives, the boy who cried wolf may inadvertantly (or intentionally) blunt our capacity to feel moral outrage at genuinely outrageous things.
Moral outrage expressed in public now seems so cheap it can be tempting to think that whoever is most vehement in publicly denouncing anything at all is likely secretly guilty of instigating the same thing themselves. That doesn't make it so ... but the temptation is understandable.