Earlier quoted context omitted.
Biotech as a whole and its misuse by fanatics (or public servants in states with dubious moral …) is a massive concern for the 21th century, but I don't really think prions deserve a special place in this list. There's way too much scary things in here (gene drive, artificial viruses, intentional smallpox spreading, etc.)
That may be the case but it's a different issue than "Why are prions more of a threat to humanity than they were 4k years ago?" With that said I sort of disagree with you. Prions are particularly attractive to a hypothetical bioterrorist due to the difficulty in detecting them, their durability and also the delay on effects. As I said above, once you know you have a problem it will be too late. Keep in mind these are…
Terrorism is about fear, and that comes with spectacular actions even if it kills relatively few people, not with stealthy poisoning of big population.
You're not gonna have anything remotely as impactful as 9/11 with prions, even if you killed a million people in the long run.
Is it a good weapon for a nation state going at war, or committing a genocide. Definitely yes! But it sucks for terrorism.