Apart from necessary technical knowledge, there is one more reason: most radical social movements has often started on technical universities.
Reason for this is simple. Technically oriented people tend to underestimate how society works, and believe that it is possible to change it easily. This attitude was also seen in XIX century, when mathematicians tried to apply mathematics rules to social problems. It should mention that this never worked. Not because mathematics is wrong, but society is simply too complex to be modeled that way. (Or, it could be modeled mathematically, but results would not be spectacular.)
Or to say it in other words: you have an intelligent but socially incompetent person, who believes that everything is easy to fix (hey, there was no WinXP that he could not attach a SATAII disk to!). He is highly dedicated, he believes that his position in society won't be appreciated as it should, and he believes that one bomb could actually solve something. Doesn't this sound like a good candidate for a terrorist?