In journalism today having access to "important" people might be the most important factor in how successful your career will be. It matters more than finding and reporting the "truth," even though everyone in the field will say that the latter is more important.
It was a feather in Reilly's cap for years that Lance liked him and would talk to him whenever Reilly wanted to within reasonable limits. That would have changed had Reilly ever questioned Armstrong's honesty. So there's a nice, symbiotic relationship in which Reilly thinks he's got the upper hand on all of Armstrong's public critics because he gets his stories straight from the horse's mouth or at least from some end of the horse.
Now Reilly sees he's been played for a "chump,' his term, and millions of people know it. Guys like you, who had no access to Armstrong like Reilly did but were calling him out anyway turned out to be right and Mr. Inside Story couldn't have been more wrong. That's going to tick a guy off.