Biologists who are working at the cellular level or above can continue their research without paying much attention to design, because above the cellular level organisms are black boxes, and design is difficult to prove. So those who labor in the fields of paleontology, comparative anatomy, population genetics, and biogeography should not invoke design until the molecular sciences show design has an effect at those higher levels. BUT each biochemical case must be considered on it's own as a result of purely natural means or as a result of design. As he points out the Intelligent design concept is old. It has kept changing as science progresses.
Intelligent design is there to fill in the gaps.
As more research goes on these gaps may slowly be filled until it is possible not to appeal to intelligent design. The author mentions that the Big Bang is consistent with the Judeo-Christian concept of beginnings, but not consistent with other religion's concepts. However he doesn't mention that the end is inconsistent with the Judeo-Christian concept of the end. Astronomical evidence shows that our universe will have no end. Mr. Behe's speculations are way out.