I'm buying Slate an Occam's Razor for Christmas

Am I the only one that is puzzled by this 2-page Slate article worrying about the source of the polonium used to kill Alexander Litvinenko?

I thought that it was pretty much assumed by everyone that the Russian government offed Litvinenko. Obtaining that radioactive isotope might be difficult for most people, but I assume it is not a problem for the Russian government as most of the world's polonium is produced in Russian reactors under Russian government supervision, as the article helpfully informs us. So why the speculation about black market polonium getting into terrorist hands? I know that Slate always tries to come up with a "but the real story is..." hook, but this is one contrarian angle that just doesn't make much sense.

If anything, the difficulty of obtaining polonium almost seems like a signature touch -- Litvinenko might have had many enemies, but how many could get their hands on polonium 210?