Yes, I dispute the statement that peoples' accounts of their own motivations are generally unreliable.
Then I suggest you educate yourself about social desirability bias. It's well known -- and obvious just from general observation -- that people have a strong tendency to self-report information which puts them in a more flattering light. If you have not taken this into account in your assessments, then it's fair to say that any conclusions you have drawn are suspect.
It's the sentence ending in footnote 22.
Ok, so apparently a typical example of the best evidence of your claim is a polemic in which someone cites the Dresden bombing as a rationale to criticize Western attempts to purge Nazis from post-WW2 Germany. There is no evidence as to how much such events actually motivated anyone; it's just an argument someone is making.
Your evidence for Sipursky Rage is quite weak as to Nazi Germany and extremely weak as to the situation in Syria:
A few anecdotal reports of terrorists who make the self-serving and unverifiable claims that they were motivated by Western misdeeds is so weak as to be ridiculous.
Anecdotal reports by terrorists is the best data we have available. Weak evidence is still evidence. We should update on whatever evidence we have, and avoid dismissing it out of hand and calling it ridiculous. As aspiring rationalists, we need to orient toward the truth, and avoid confirmation bias.
Here's my op-ed that uses long-term orientation, probabilistic thinking, numeracy, consider the alternative, reaching our actual goals, avoiding intuitive emotional reactions and attention bias, and other rationality techniques to suggest more rational responses to the Paris attacks and the ISIS threat. It's published in the Sunday edition of The Plain Dealer, a major newspaper (16th in the US). This is part of my broader project, Intentional Insights, of conveying rational thinking, including about politics, to a broad audience to raise the sanity waterline.