Isn’t it traditional for terrorist organizations to claim responsibility? ISIS claimed all their ops. After all, that public declaration of “yes, we did this, and we’ll do more if [x]” is how terrorism works—you’re hardly going to intimidate anyone into following your agenda by saying you don’t ever do anything.

I’m not saying that the overall position is wrong, just that “the perpetrators of a terrorist act would avoid claiming responsibility” is weak logic.