Is ISIS responsible for soldiers of the caliphate attacking Texas event?

Bizarre story from Texas. 

Anti-Muslim group holds Prophet Muhammad cartoon event. Two men show up to attack the event, Elton Simpson and Nadir Soofi, and they are shot dead.

Now, ISIS is claiming responsibility for the attack at a center near Dallas that was exhibiting cartoon depictions of the Prophet Muhammad.

But, are they? Was there any command and control? What there any actual attempt to bring Elton and Nadir into the fold? I doubt it. 

It’s publicity. Anyone purporting to be Muslim and act against the infidel will be claimed as “a soldier of the caliphate.” The truth is that they are likely disturbed young men who are inspired by the existence of ISIS, Al Qaeda, Boko Haram, and the like. So, in a sense, ISIS is responsible but not in the way that we would ordinarily use that word. 

We do not, for instance, hold parents to be responsible for everything they their children do. Nor is Canada responsible for all of the actions of all of its people. We generally think of responsibility as being a direct result of decisions that have power.