Interesting thread, especially the information from those who clearly know what they are talking about.
The rants about airport security are misguided, as several have pointed out. The purpose of screening passengers, crew, baggage, cargo and mail prior to boarding, and ground staff working in the RZ, is to prevent acts of terrorism and/or piracy against passenger aircraft in flight, not to save the world from assassins. No-one is ever going to carry out either of those with a few grams/milligrams of Polonium 210, undetectable in a container anyway.
You could of course say exactly the same about some of the other things that are banned, and you would be right. But that's another issue.