Is this a rhetorical question? A lot of (most?) adults aren't immune to this sort of manipulation, let alone kids. See: Fox News, cults in general, and so on.
It's not just about bad information, or opinion stated as fact, or whatever. Whether it is designed to indoctrinate and radicalize, or whether it "simply" evolved that way as a meme (in the Dawkins sense, probably clumsily applied), that's how it works. These people haven't just been taught incorrect facts, but whole distinctive patterns of speech and thought that serve to reinforce their own commitment and induce it in others.
It's an arms race, and in an emotionally vulnerable state I doubt even the sharpest kids (or, again, adults) are fully armored against it.
It sounds like a joke, but this content is purposefully created and disseminated for the purpose of "going viral," so that it can spread itself. It's created by people who either have only consumed like content and want to spread their virus ("my personal opinion based on internet reasearch is that...") or people who actually create this stuff on purpose to push the agenda of their employ.
The Dawkins meme analogy is brilliant, we just hadn't really seen it used as a weapon until pretty recently.
Memes have been a core part of political strategy for decades. Human beings have never thought fundamentally based on facts, and they likely never will. All parties do it to varying degrees, but it's very difficult to see it when it lines up with your personal ideology.
I guess one part of it is that alt-right sources pre-inoculate readers against potential sources of truth, by calling them liars.
For instance, Snopes is often held up as a good place to go to debunk things. Except one of the things you learn early on from even moderate right-wing sources is that Snopes is apparently massively left-wing-biased, and since they've been wrong or biased on a couple of things, it means their entire worldview is suspect. And of course you can't trust any of the lying mainstream media.
So at that point you hit up Google and - surprise - the only sources of truth remaining are right-wing sites, and left-wing blogs trying to discredit them; but the left-wing blogs have a very obvious political bias, and they're just written by some guy in a basement, so of course they're lying too. So you're left with only writing that confirms what you suspected in the first place.
I guess the only way out of that is to be smart enough to notice the internal inconsistencies or plot holes, or that some of the facts that are being asserted simply cannot be true - and then principled enough to care about that. Both of those are probably quite high hurdles for a casual news-reader.
Certainly in less extreme circumstances, when I have occasionally checked moderate right-wing sites to fact-check my own left-wing news sources, I have found it very hard to trust that those sites might be correct, and that my favourite news site might be mistaken. And I don't do that anywhere near as often as I should do.
In part I would say it is because facts is very rarely as clean as we would want so the norm is to mix opinion and facts in a way to create a easy to understand narrative. In addition information tend to be simplified by making things more extreme, like turning "a few" to "all" and "sometimes" to "always".
The article brings up several topics which education did not give the boy enough tools or information to properly investigate. The relation between religion and violence. The relation between religion and usury laws. Wealth statistics and distribution and the extreme amount of different way it can be presented based on different narratives. Gun laws in relation with crime statistics. Human rights and how/why there exist sex differences in the law covering rights and responsibilities for women and men during and after a pregnancy.
Those are quite complex topics and the issue as I see it is not that he was unable to determine which sources from Google is right or wrong, but that society is presenting them as easy facts with right and wrong narratives.
Why did he believe in those biased sources of info? How come he didn't have the skills to determine what is fact and what is opinion stated as fact?