I have a doctorate in psychology thats why. The personality assessment he provided does not indicate signs of psychopathy.
There is a checklist but it takes years of evaluation to determine if a patient is psychopathic.
I do plenty of forensic evaluations myself. I don't know what he used, probably an MMPI or something. I agree that testing is only so reliable, but we don't have him here defending his assessment. A full psycho-social goes along way. This kid could have a long standing diagnosis of RAD from multitudes of psychiatric admission in childhood, numerous stints in partial hospitalization programs, and alternative school records. We don't know the full context of what was going on when he was being assessed either. When it comes to personality disorders face-to-face assessment is the most important diagnostic tool; especially for the B clusters. It's not ethical or valid to diagnosis someone over an internet forum.
I'm also not saying this kid is or isn't any diagnosis. I'm just saying we don't have to tools or ability to adequately diagnosis him, or question someone who has treated him in a real-life context.