Personally I think it has more to do with the fact that engineers are trained to follow rules and so it attracts people who are happy to follow rules without necessarily questioning them or completely understanding the reasoning behind them.
On the other hand scientists will question every rule you give them and even when they believe that the rules might be right they will still spend their time poking them to see if they really do apply everywhere....which is why we can be so annoying at times especially to those trying to use toxic, religious dogma to persuade others to commit irrational and immoral acts.>
I don't think I agree with this generalization.
Most engineers I know aren't the blind rule follower types. They are looking to creatively apply the rules they know about to solve interesting problems, and if they don't know, they are happy to experiment and make their own rules-of-thumb. Rather than follow the rules, they question the rules all the time to find a way around the rules.
On the other hand, many scientists I know are the "lawyer" types that want to kill all creativity that don't follow the rules (even if the rules have to be "tortured" to apply in that situation). I've known a few that would even get borderline violent when people were speculating outside the box.
I think that the common personality type that makes both scientists and engineers easier targets for terrorist recruitment is experience with social isolation and elitist attitudes that make it easy for them to dehumanize people that don't think like they do. Couple that with standard recruiting techniques and those people are easy to re-baseline (the key to radicalization).
The process of radicalization of a target generally starts by attempting to break rules that the target holds dear. Safety, fairness, corruption of heroes, falsification of memes, etc are all standard techniques here. Since no "rules" are universal, it's usually easy for a trained handler to pick low-hanging fruit here.
Next the handler introduce the target to a benign organization, it's important in this phase to help shift the identification to a different group. Helping out in a cultural center, or volunteering to assist in charitable causes will help the target empathize with the plight of people sympathetic to the terrorist group. The more socially isolated the person was before, the easier this processes (don't have to break as many existing ties).
During this assimilation time, the handler will probe how much the target might be willing to rule breaking by feeding them more propaganda to get them to normalize and accept the new rules (e.g., it's okay to hurt these specific people because they deserve it).
Finally, there's the "requirement". Involve the target in an operation where they don't have to do much of anything, but see if they run. If they don't run, the handler has likely created a new terrorist. It could be attending a protest, or spraying graffiti, or adding a "like" to radical facebook post. This is often called the "foot-in-the-door".
Then there is the "escalation" stage. Generally, promises are used in this stage (guarantee of appreciation, acceptance, heaven, virgins, glory, whatever) and involves helping prepare for a simple low-risk operation. The act of asking to help prepare is generally an easy ask, the target doesn't have to do the operation, but feels like they are involved. For engineers and scientists it might be asking to consult on some technical aspect or give ideas about how they might overcome some technical problem. Maybe they want to a DoS attack on the enemy during a religious holiday. They don't need the answer to the problem (they will generally already have it figured out), but they make the target feel like they are contributing something (e.g., hey that was a good idea, maybe we'll think about that next time).
Since engineers and scientists naturally enjoy solving problems and sharing their knowledge, they fall into this trap easily. Once they have fallen in they find themselves complicit with operation and no easy way out. The addiction to being appreciated for being helpful is powerful. Cognitive dissonance generally takes over and they are trapped. The journey to the dark side is complete.