Whilst I may not agree with a lot of what you write, in this article you have hit the nail squarely on the head.
Those who are implementing and carrying out the Security Theatre are not interested in the real risks involved, they just want to be seen to be Doing Something in order to justify their "need" for greater powers and more money in order to build their personal empires a bit bigger.
Several of the possible threats you mention are ones that I have thought up myself as potential attack methods and I don't even have the background you do, just an interest in science and a knowledge of how people think (or don't think!) so we're left with the conclusion that either a) the terrorists have nobody with any brains to think of these things or b) they have thought of them, but simply do not have anyone able or willing to carry them out.
I know which my money is on...