4 ideas
From 1999, when Lance Armstrong won his first Tour de France after surviving cancer, Irish journalist David Walsh of the Sunday Times publicly doubted the win and spent thirteen years gathering evidence of doping, including testimony from Emma O'Reilly and Betsy Andreu, which he co-published in the 2004 book L.A. Confidentiel. Armstrong sued, the Sunday Times settled a libel case, and Walsh was frozen out by the team and much of the press.
Beat journalists who rely on a subject for interviews, access and a good story are pulled toward protecting that subject, because asking hard questions costs them the access their job depends on. The cycling press corps knew the sport was saturated with doping but chose the cancer-comeback narrative, and treated the reporter who questioned it as the problem. When a story is commercially and emotionally rewarding, the people who cover it become invested in keeping it true.
In a field where the competitors you have beaten are later caught cheating, a clean athlete beating all of them is statistically implausible. The anomaly is itself a reason to investigate rather than to celebrate. This lens moves the burden of proof: extraordinary dominance in a compromised system calls for scrutiny, and an inspiring backstory should not stand in for evidence.
A powerful subject protects a lie by using a sympathetic personal story, here cancer survival and a charity, as a moral shield, so that doubting him looks like attacking a survivor. He adds libel suits, public smears and ostracism of witnesses, which raise the cost of speaking up.