I don't know about the level of detail in the original paper but the CNN article doesn't really give that much away or at least, nothing someone who *really* wanted to contaminate the US milk supply wouldn't already know. If 9/11 showed the world anything it that these guys can, and do, do their homework.
The part about what toxin to use is like saying "to build a nuclear bomb, first you need Plutonium". Botulin was probably used in the article because that's what the paper said. Realistically, you could use any number of toxins. Any even remotely organised terrorist organisation would not only know this, they would know how to aquire it. Actually, botulin would be easier to aquire than that article makes out. You guys all know what Botox is, right? Yup, Botulin. They use its neurotoxi nature to paralyse the muscles in the face to smooth out lines and wrinkles. OH NOES!!1!! I'M GIVING INFO TO TERORISTS!!!11! ...

The only thing in the article that highlights a potential weakness is saying milk distribution is largely unguarded but I'd imagine that would already be obvious to both you and I
and potential terrorists. Short of giving every milk truck and depot in the country an armed guard/escort (which kick up a whole other "right impingment" debate) there isn't an awful lot they can do against anyone
really wanting to contaminate the milk supply.