The article doesn't say anything about Pr(Dislikes Rewards), but rather claims to have measured P(Diminished Response to Rewards | Clinical Depression Diagnosis) > P(Diminished Response to Rewards | !Diagnosis).

It's an 84 person study, done using EEG (a very rough measure of electrical activity in the brain), claiming a result largely related neurotransmitter release (ie not the sort of thing EEGs are usually used to measure). You should take their claims with a huge helping of salt.