How could he be 'very rational' and also 'threaten people to become his friends'?
Something similar is common in victims of trauma as well. The trope is the woman with "daddy issues", which are more complex, who try to fill a void they have with sexual relationships. Instead of seeking an absent male relationship, they manipulate to get a "friendship", and are often very skilled at meticulously building this friendship, without the emotional connection that governs our behavior. They are seeking a means to an end - which may include just feeling something.
I had an acquaintance like this, who became a very scary individual as he became an older teen. I cut him out completely at 13 when I suspected he harmed a neighbor's cat.
As the author of the article stated, it doesn't make her evil. But she is dangerous, as her motivations are different her behavior is probably governed more by her executive control part of the brain, which is high labor and highly rational. "Rational" sounds great to engineers, but people make very disturbing rational decisions when they build a system of unusual assumptions.
You might be asking "but if he was rational, couldn't he see that blackmailing is incompatible with friendship?". Well, if he wanted the trappings of friendship (having a friend group, playmates, hanging out and so on), and not some "genuine bonding", it's not that incompatible.
You'd be surprised. Some get friends literally by being bullies. Others then want to be their friend to avoid being their target.
> he was very rational and threatened other children to play with him and treat him like a friend
My emphasis. He’s not forcing people like him, because you’re right, you can’t force that, he’s coercing people into acting like they like him.
The point is that since he (supposedly) can’t feel the feeling himself, or can’t understand it, all he has to go off of is what he observes - i.e. the behavior - and you can absolutely force a behavior.
I mean come on, there are plenty of adults who think that that's a perfectly rational approach to getting what they want.
True, but TBF, it takes experience to realize that, and the psychopathy kind of hinders getting that experience? (Reading could also help, but not in the same way)