One of his main defenses seemed to be, why would he take something that would cause him to break down? He even specifically mentioned the negative affects of steroids on flexibility. And Clemens seemed to act as if he never suffered under similar issues. Any injuries that caused Clemens to break down later in his career could be related to his age, and not at all to steroids use, but I think it's pretty clear that Clemens did suffer from such injuries.
Here are some actual excerpts from the interview. They aren't exaggerated, but rather taken word for word from the transcript.
Wallace: Why would Brian McNamee tell the truth about Andy Pettitte and lie about you?
Clemens: Andy's case is totally is, is totally separate. I was shocked to learn about Andy's situation. Had no idea about it....
Clemens: Why would I want to get tight or lose my flexibility, put something harmful in my system that's gonna cause me to break down when I've had a 24 year career?
Wallace: Look, because you're at the end of your career, and because you you don't want to give up the career and give up the fame and so forth. So if it's necessary to stick something into you—
Clemens: I didn't play my career to get fame or go to the Hall of Fame or worry about all that. That's nice. That, all that's nice. Again, it's not who I am. I've worked my tail off to get where I'm at. I'm not gonna put something in my body for a quick fix that's gonna tear me down.
Wallace: In two of the three years that McNamee claims that he injected you—'98 and 2001 you won 20 games and the Cy Young award as the American League's best pitcher.
Clemens: I won—in 1997 I won the Cy Young Award. 2004 when he supposedly, I wasn't doing it.
Wallace: Yeah, but these are the years in which McNamee claims that he injected you.
Clemens: It didn't happen. It didn't happen. It just didn't happen.