However the danger is in the knowledge itself so what happens when this red line can be crossed and someone is able to put together a method of mass destruction with readily available equipment? I believe that's what he's talking about.
I know. Even arguing that cheap, easy-to-build WMD would sooner or later inevitably fall in the hands of extremist, nefarious individuals or groups, what makes them more dangerous than clumsy medical students entrusted with deadly viruses, nuclear engineers who are drunk on the job, paranoid military officers, or politicians who feel millions of dead are a small price to pay for power and supremacy? I am actually more concerned about all those categories than any terrorist. So far, the number of victims in a nations vs. terrorists death contest is heavily skewed in favour of nations.