presenting symptoms of psychological disease sufficient for appropriate dedication to a mental institution
- fit to-be certified as insane (and addressed properly)
- with the capacity of becoming guaranteed or certified
1846, from certify + -able. Meaning "so deranged as to be certifiably insane" is recorded from 1912.
The good news is this rag of a newspaper doesn't seem to buy Mr. Youngblood as a certifiable clairvoyant.