Dustin Eisworth's criminal record indicates he went to prison for aggravated assault resulting from a bar fight where he blinded a person with a broken beer bottle. However, the state of Oregon does not have an aggravated assault statute, and in states that do, it is charged for assaulting a law enforcement officer. In Oregon, a person committing an assault that results in such severe injuries would be charged with assault in the first degree, a class A felony, which carries a maximum sentence of 20 years in prison.
While in prison for assault, Dustin Eisworth killed another inmate, was charged with murder and sentenced to an additional seven years in prison. However, in the state of Oregon, the minimum sentence for murder is life in prison with the possibility of parole after 25 years. Which means Dustin should still be in prison and wouldn't get out until 2034 at the earliest.
Reid explains what exposure therapy is, but as the BAU had a case with exposure therapy at the center of it a few seasons ago, the explanation shouldn't have been necessary.