Having read the indictment, this group of wannabes don't seem like they have the ability to tie their own shoes. But in the days to come we will see if they were a valid threat or not.
Reid didn't have the ability to light his own shoes, but he was still a terrorist. Also, any idiot can make and detonate an explosive device.
They don't have to be very bright. Just vicious enough to want to kill total strangers drinking coffee at their desks some September morning...
They obviously thought they were in touch with somebody who was going to plan things for them, and this is what AQ has been looking for: domestic people who are dumb enough and violent enough to let AQ use them for operations here. Fortunately, dumb also means more likely to get caught (like the shoebomber, Muslim convert Richard Reid, whose IQ was probably only a little higher than that of his shoes).