Joe has truly never been right about anything ever. But he has always been a prolific liar.
I wouldn't be surprised to see him pass a lie detector test. He likely believes a lot of what he regurgitates. For instance, he denied the mental observations contained in the SC Report, citing that he does remember where his son died. I noted that no reporter dared ask him 'Where did your son, Bo, die?'
I bet he would have said he died in Iraq during the war (not in Walter Reed Hospital a few years later.) I get the impression that he really believes that. Such flights from reality help to explain how he can be so confident of his 'rightness' in the face of his crushing failures. (❓)
In short, lovable old Uncle Joe is probably a mental case.