Confession may be good for the soul, but it's usually not a great career move as any devotee of "Law and Order" will tell you. The confessors usually get hauled off to prison.
Maybe Lance Armstrong will be the exception to the rule and certainly prison isn't in his future, but in the real world of crisis management, reputations and careers are not easily restored by belated confessions, no matter how sincere. And while every case is different (For example, Tiger Woods did not cheat competitors out of prize money or alter the outcomes of tournaments), Armstrong's mendacity and corruption are on historic levels. He didn't just cheat, he denied it for years, he sued a newspaper - The London Times - that exposed his cheating, he destroyed the careers of old friends, and he organized a cover up of epic proportions. Tiger may be a reprobate, but he didn't leave dozens of lives in shambles.