Mindreading terrorists

Security technology writer Bruce Schneier writes:

the theory says that people infer the motives of an actor based on the consequences of the action. So people assume that the motives of a terrorist are wanton death and destruction, and not the stated aims of the terrorist group ... This certainly explains a great deal about the U.S.'s reaction to the 9/11 attacks. Many people -- along with our politicians and press -- believe that al Qaeda terrorism is different, and they're just out to kill us all.

The question is whether we should judge al Qaeda terrorists by what they say or what they do. The cited paper says that terrorists are ineffective because governments ignore the stated wishes of the terrorists. (Here is a sample of what al Qaeda says.)

I don't believe in mindreading, and I don't believe in assuming that the stated goals of a bunch of terrorists are their real goals. Why believe that a bunch of terrorists are telling the truth? If they are willing to murder innocent civilians to advance their agenda, then they are surely also capable of lying.

If ignoring the stated goals of the terrorists is causing them to be ineffective, then so much the better. Schneier seems to be arguing that this means that we are wrong about al Qaeda, but as I see it, it implies that we are right.