The bit about "Absolutely no uranium, plutonium, thorium, or radionuclides derived therefrom" was actually not inspired by the "No tea" inventory item in The Hitchhiker's Guide to the Galaxy. It should have been. I wrote that part, and I've played THHGTTG, but there was no causal relationship between these two events. I put in that inventory item because there was a "fission" verb, and I wanted to be explicit about the fact that you do not have any critical masses of fissile elements anywhere on your person, nor any elements from which you can breed fissile isotopes using some spare neutrons.

(I probably would have made the radionuclides examinable, if I hadn't been too busy making all the verbs apply to pigs. There's probably a lesson in here somewhere.)