Not at all. I know for a fact that he is on gear, which is why he'l never bring this to court.
Thanks MindSpin - bear in mind though, that you "knowing he is on drugs" will not in itself be a sufficient defense if he decides to sue you, or Ron from GetBig.
Basically the procedure is that he would bring an action claiming that your statements and GetBig (as the publisher) have caused harm to his reputation and character. He would claim that as he is in the fitness industry, his financial losses caused by your claims are substantial, and also claim for hurt feelings, distress, legal costs, loss of future income, exemplary damages, etc etc. The onus then falls on you, to be able to prove the truth of your statements (and unless you can do that there is a presumption of guilt on your behalf).
I of course don't know who is right on this issue, and if he really is claiming to be nat when he's not, then good on you for exposing him, but just letting you know that you better have some pretty conclusive evidence to support your statements.