Nobody is safe. That’s my takeaway from an exchange of email I had Thursday with Brad Horn, a spokesman for USADA — the U.S. Anti-Doping Agency. I queried him on how 59-year-old cyclist came to be sanctioned for refusing an out-of-competition drug test. I wanted to know where he was when he was solicited. (Brad doesn’t know yet.) But he said: “Ultimately, this case was the result of target testing, based on credible information received through USADA’s Play Clean Tip Line. USADA makes available a number of ways to report the abuse of performance-enhancing drugs in an effort to protect clean…