If someone evil has access to the water supply, is radioactive material the worst they could do? that'll, what, give some people cancer which is really bad but it'll take a while to get them. If people wanted to be shitheads, they could already dump arsenic or LSD into the water supply, or any number of others things. that are already available to them right now! Have you personally tested your taps chlorine or flouride or lead levels recently?
Except most people don’t have industrial levels of arsenic, LSD, or other highly toxic substances stockpiled in their homes. Nor do they have a way to obtain it without triggering a visit from a swat team. Which is exactly what this comment chain is discussing. The potential for harm when you don’t have to go anywhere but your own basement/a few neighbors to obtain enough enriched uranium to create a superfund site.