I think a lot of people like Dunphy full stop. I'm a fan of his (sometimes) and enjoy his irreverant voice on occasion.
I don't really think you can really equate athletes taking performance enhancing drugs with Dunphy's admiited occasional drug habit to be honest.
I didn't see/hear his statement but it's only his opinion, and to be honest I think he is only mirroring what a lot of people think about the Olympics these days anyway.
I'm quite anti-drugs myself, having seen the devastating effect they've had on past friends, but it's his choice if he wants to take them, just as it's his choice to turn up for work pissed (of sorry...tired) sometimes. It's RTE's choice to keep employing him too...and they do. I think that should tell you something about the popularity of the man.