What it sounds like to me, and something I've wondered from the beginning, is if he had high functioning autism/aspergers. He sounds a lot like a young man I know. Not very socially adept, but considered sweet and harmless. Obsessions or fixations (searching for perfection) but not good on follow through. A strange dichotomy: trusting and naive about the motives of some, but frustrated by the lack of freedom given by family members (relatives trying to give advice about romance or jobs, and this young man being angry about it, feeling he knew better than all of them).
Now, I am describing my acquaintance, but I see so many similarities with SK. I also know that families are sometimes very reluctant to admit there is something "off" about a loved one. 30 years ago it wasn't common to seek a diagnosis or treatment for a "quirky" personality and now most parents want early intervention in cases where kids aren't meeting developmental milestones.
I know we have discussed this before. I work with autistic/asperger people. I also have a daughter with autism. and did you know Bill Gates has aspergers?
Often people think people with asperger's, are confident, blunt, and have big egos. They seem to be perfectionist. They often have a interest in one thing, and seem to know alot about their interest. They usually do not have many close relationships. But I do know many that are married. And many that do well. I hear people describe these people as : nerds, confident, big egos, into their selves, etc. Before we know their disability,we see them this way.
I do know people that are older, that were not diagnosed for asperger's until they were older. Maybe because they have a child,friend, or have been educated on this disability. Now, that autism is now one in every ninety one births, we are learning and understanding alot more. Anyway, I am not saying SK has asperger's/autism, just trying to give a little info.
By the way I am ADD. I will not go into that(LOL).