@BillRM,
Who is to say they would be wrong. You are assuming that any attacks by ISIS against the American homeland would necessarily be met with an attack that would wipe them off the face of the earth.
I tend to agree with you that there would be a military response to such an attack, but a terrorist in the Middle East might, by watching CNN, come to the conclusion that we have a president who either can't or doesn't want to pull a trigger that might lead to another ground war, and that as a people, we've come to the realization that such attacks are never going to stop until we pull out of that part of the world completely.
Again, I think this would be a mistake on his part, but do you believe that even if we were attacked on US soil again that there wouldn't be a lot of voices arguing against military retaliation?