This is irrelevant, because a. DeCoster wasn't trying to address terrorism but the expansion of the powers of the state, and b. no one is likely to come and ask me how to solve the problems anyway, ; however, since you asked politely (unlike some) I'll give you the most obvious (obvious to all but the FAA that is)
I don't know why people have such a problem understanding this point. Rulers become rulers because they want to live in luxurious circumstances; they aren't going to let some silly sanctions stop them. The result isn't just that only the innocent and poorest suffer, but that they are more likely than not to be strengthened in their support of the ruling regime against those who imposed the sanctions.
Technology can help design a fusilage that will not be poked through by bullets. But the problem with a cabin full of armed passengers is that of stray bullets hitting other passengers.
One to three undercover air marshalls per flight would be better with an impenetrable cockpit.
Free trade with every nation? I don't think so. Why should we empower dictatorial regimes by trading freely with them? Could you imagine Castro being economically powerful?
If you want free trade, which is a great thing, you would need for the countries we trade with to have some sort of market economy to match the trade. Otherwise, you only prop up their dictatorial governments; the people of which will not benefit.
Lastly, be careful not to fall into the trap of leftist propaganda of their poverty being the reason for their hatred of the United States. These types are deliberately taught from a very early age to hate us.
Force must be met with greater force. Period.
But at least you have given a shot at a solution (although I had to ask for it). I can't say that for anyone else who is of the Rockwellian mind.