Hello!? I DID the math. One in ten thousand does mean ten thousand out of one hundred million. Vaccination against smallpox as a preventative measure, in total absence of the disease would result in 25,000 deaths in the USA.
30% die of the disease? First you need to be exposed to the disease. The 30% figure is also misleading because that would be 30% without treatment. With treatment more than half of the fatalities would not occur.
Again sure smallpox is terrible, but prevention could actually be more fatal than the disease presented in weapons form. But the USA is better equipped to fight the disease than our enemies, this makes the deployment just a bit troublesome for any would be terrorists.