I wrote before that I won't get into remote diagnoses. A few fellow PPRuNErs that know me, know me as qualified so to do.
The issue here is insight - the self-awareness of the need to seek advice. Our boy has in my estimation no insight, and sees himself as the tortured, misunderstood genius. It's not really Mitty'ism. He truly believes what he writes, with all his soul. Arguably, the more we throw the hard facts at him, the more he feels emboldened in his crusade for truth and beauty.
Only family can most likely help...and they may or may not be in cahoots, fellow sufferers, monumentally stupid or suffering harassment to comply with the young 'un's behaviours. It's not pretty.