That's an interesting story about the young man who was trying to recruit your son, especially the part about how you later leaned the man's home life was a mess. Who knows, but perhaps some kind of psychic damage is the root of some of this twisted thought. Or perhaps there's a genetic predisposition toward xenophobia, paranoia, and hatred that is triggered by an event. Something is going on with these people, and it's not normal, in my opinion.
As an example, prior to making this post at DU I engaged with someone who was commenting on the Evalion videos. The man was a Holocaust denier. He said that if someone could show him photos of where the Zyklon B was poured into the gas chambers, he'd change his mind on the subject. So, dutifully, I found a photograph of one of the holes through which the poison was poured. Within minutes, he responds saying that the gas chamber in the photograph was "a fake." Further, he argued that Zyklon B could only dissove in water, so its use in the gas chambers, he argued, was impossible. Of course, that assertion is utterly false: Zyklon B is a form of hydrogen cyanide and it vaporizes at room temperature. I told him as much and even directed him to a chemical fact sheet detailing the molecule's properties.
None of these facts mattered a whit. There is something twisted deep inside these deniers that is impervious to facts.
You summed up this girl and her channel well: It's "sick, sad, and horrifying, all rolled into one small package."