I think that's kind of the point I'm making, isn't it? You might know in your rational mind that the guy used to dope. And you think you know it's still the case now (though, really, other than for a small coterie of Armstrong's inner circle, what does 'know' mean in this context other than believe very strongly?). But then there's the guy himself, being your mate, making you feel good about himself and your position in the world, and there's your younger, 13 year old self reminding you how impressed you were back then, and there's this desire to hope for the best, that this time it's different, and there's the money you make out of the whole circus, and the vested interest in the (what you feel) is the bloke's success at raising 'the profile' (read: your wages) of the sport, then there's the doubt that the thing staring you straight in the face is true when the guy denies it so convincingly, and makes you feel so good about yourself.
And so - in one particular moment, when someone is asking you about him - you give him the benefit of the doubt, and you say 'oh yeah, I love him, he's been great for the sport'.
It doesn't mean that you don't have any scintilla of doubt. It doesn't mean that the only explanation is that you are now obviously doping. It just means you are a real person, with real, sometimes contradictory emotions, and that's how you were feeling at that particular moment in time. And maybe your head has been turned.
Would Wiggins be the first person to the history of the world who's given someone they love/admire the benefit of the doubt? Because I always thought that 'love is blind' cliche is rooted in some sort of recognisable truth.