You're correct, but that says more about the definition of "person of interest" than it does about the kid's dangerousness. For example, my parents came to the US from Lebanon. Aside from the fact that my family isn't Muslim, the profile fits me perfectly. I'd bet good money that it fits the vast majority of immigrants who still have family in the old country.
The other thing worth remembering is how the person of interest to whom the kid is linked became a person of interest. He posted a comment on reddit speculating about how easy it would be for terrorists to wreak havoc by hitting arbitrary soft targets throughout the country.
Like hiring, catching terrorists is a game where you should be willing to take a lot of false positives to avoid one false negative. But it can go too far, and people's worry is that it has done here.