It has been noted here (and here before that Osama Bin Laden and Yassir Arafat and Mahmoud Ahmadinejad were all Civil Engineers, but according to sociologists, that is not mere coincidence, it is a sociologically predictable phenomenon.
I have long said Transportation Engineering is the last bastion of socialism in the US (almost all the roads are state-owned, and queues are quite common due to undersupply and lack of a price signal, attributes of a socialist economy), but who knew we civil engineers were also the source of Islamo-Fascism. Of course, to a post-modernist those are both the same, as being parts of "totalizing narratives" as my Marxist Geography professor would have noted (not that he was a post-modernist).
Perhaps the critical question is why do would-be terrorists want to have engineering as their back-up job? Is there something about the terrorist mindset that causes engineering to be an appealing second choice should bombing innocent civilians not work out or not pay as well as hoped? Perhaps the skills obtained in trying to make bombs (wiring, systems thinking, etc.) and destroy are easily transferred to making durable structures.
Or maybe we should ask what it is about non-terrorists that make them less likely to be engineers? Clearly engineers are in general useful to society, what personality trait are non-terrorist wannabes missing that discourages them from undertaking an education in engineering.
The original article would appear to be reasonably well-researched given the dearth of data about the nebulous underworld. Yet of course correlation is not causality.