One might order a home-built kit to be delivered to a street address, but Cessna does not build or sell airplane kits.

I really question how much damage a terrorist could do with a Cessna. And what kind of Cessnas were they? A C172, for example, could barely get off the ground with 4 passengers.

Were they new or used? The only ones you could buy "off the Internet" would likely be used ones, I think.

I wish the original poster had posted a link to the actual article, or at least copied the article for us to read. Like you, I have a hard time taking this "threat" seriously.