I think Schneier is one of the most intelligent voices in the debate on terrorism but I'm not convinced you sum up his position entirely accurately. I had a browse around his site to see if I could find some specific data to confirm your claim and had trouble finding anything. The best I could find was Portrait of the Modern Terrorist as an Idiot but it doesn't contain actual data. I'm rather confused why you linked to the specific blog post you chose which seems largely unrelated to your claim. Do you have any better links you could share?
Note that in the article I link he states:
There is a real threat of terrorism. And while I'm all in favor of the terrorists' continuing incompetence, I know that some will prove more capable.
In this video, Julian Savulescu from the Uehiro centre for Practical Ethics argues that human beings are "Unfit for the future" - that radical technological advance, liberal democracy and human nature will combine to make the 21st century the century of global catastropes, perpetrated by terrorists and psychopaths, with tools such as engineered viruses. He goes on to argue that enhanced intelligence and a reduced urge to violence and defection in large commons problems could be achieved using science, and may be a way out for humanity.
Skip to 1:30 to avoid the tedious introduction
Genetically enhance humanity or face extinction - PART 1 from Ethics of the New Biosciences on Vimeo.
Genetically enhance humanity or face extinction - PART 2 from Ethics of the New Biosciences on Vimeo.
Well, I have already said something rather like this. Perhaps this really is a good idea, more important, even, than coding a friendly AI? AI timelines where super-smart AI doesn't get invented until 2060+ would leave enough room for human intelligence enhancement to happen and have an effect. When I collected some SIAI volunteers' opinions on this, most thought that there was a very significant chance that super-smart AI will arrive sooner than that, though.
A large portion of the video consists of pointing out the very strong scientific case that our behavior is a result of the way our brains are structured, and that this means that changes in our behavior are the result of changes in the way our brains are wired.