That's just the diet book. However, he had a very popular radio show here in New York where he did talk about exercise a lot (esp. walking). You know what? A lot of people are LAZY and that's diets that tell people they don't have to exercise sell a lot. I think Atkins developed a reputation for a no-exercise diet thanks to some adherents but not necessaerily to Atkins.
I read his book 2 years ago, and I don't remember him placing primary importance on physical fitness, he gave it a cursory review, and as a Doctor I found that to be a shirking of his responsibility.