Radioactivity is invisible, and not detectable short of a Geiger counter. It doesn't even hurt at a dose that would eventually kill people. Also, depending on the radiation, radioactivity can make other materials dangerous.

And yes, the fuel they are talking about is a lot more radioactive than a banana or whatever.

I just worry that somebody with ill will or even just bad luck will defeat security measures "en detail", if the material is moving around in smaller parcels. Also, more people "legitimately" possessing a reactor and radioactive material will hardly decrease the risk of intentional abuse.