Feasibility of airline plot

Over on 'Interesting People', a chemist discusses the feasibility of the recent 'airline plot' which caused so much disruption at Heathrow (after it was supposed to have been foiled).

You also need quite a bit of organic peroxides made by this route in order to be sure of taking down a plane. I doubt that just a few grams is going to do it -- though of course the first couple of grams you are likely to go off before you make any more. The possibility of doing all this in an airplane lav or by some miracle at your seat seems really unlikely.

So far as I can tell, for the pragmatic terrorist, the whole thing sounds really impractical.

The article goes into some detail of the chemistry involved, and then discusses the 'slippery slope' of trying to eliminate all possible risks (you can't).

It concludes with a sanity check about the level of risk involved in various everyday activities.

So can someone tell me where the madness is going to end? My back of the envelope says about as many people die in the US every month in highway accidents than have died in all our domestic terrorist incidents in the last 50 years. Untold numbers of people in the US are eating themselves to death and dying of heart disease, diabetes, etc. -- I think that number is something like 750,000 people a year? Even with all the terrorist bombings of planes over the years, it is still safer to travel by plane than it is to drive to the airport, and it is even safer to fly than to walk!

At some point, we're going to have to accept that there is a difference between real security and Potemkin security (or Security Theater as Bruce Schneier likes to call it), and a difference between realistic threats and uninteresting threats. I'm happy that the police caught these folks even if their plot seems very sketchy, but could we please have some sense of proportion?

Update: The Register discusses the chemistry of the situation.