I agree. To be fair to Mike, he said at the outset that all he had on doping was circumstantial evidence, and that the main purpose of his story was to show that a common view of LA as some kind of saint was misguided. He isn't claiming that he can add significantly to the doping stories.
That said, i really don't know how widespread the public perception of LA as a nice guy is. The people who worship him because of his cancer work don't necessarily think of him that way. They just appreciate that he inspired them, and probably wouldn't care if someone offered irrefutable evidence that he is the world's biggest a-hole (a label that LA on more than one occasion has practically pinned on himself). So even if LA followers believed this story in its entirety (and they won't), I don't think they would change their view that his cancer work buys him so kind of immunity. And anyone else, of course, wants to hear the testimony from people who really saw something.
I hope Mike has found some peace in NZ, and that Outside paid him well for his story. To me, at least, his naivete in not getting the bike shop in writing actually enhances his credibility. He comes across to me as a too nice of a guy who is easy prey for someone to take advantage of. In my experience, people like that do not make up nasty things about others.