Interpreting one-link comments is an excercise in creativity, but making some guesses:

1) You didn't check the source for the CFR. Wikipedia links an article that doesn't mention CFR or even use the word fatal. And as recently as '08 they were discovering that what they thought was one disease is actually 2.

2) I just wrote a comment explaining why a 100% CFR would be precise but likely not accurate. In case you thought it was, take a moment to reflect that linking to a table where the CFR is 100% isn't a refutation. That number is probably precise but likely not accurate. We don't seem to be good at detecting "mild" prion diseases.

3) Even if by some miracle that table is accurate and precise ... that is one disease. If you want to bet that prions only cause one disease then you're welcome to - but I'm still willing to bet that there are other prion diseases to be discovered that are less lethal.