The "journalist" who wrote this was sloppy. He states initially they were raided and arrested because they we're perceived as a threat. That's alarming. He (or she) then later points out that they were charged for violating laws (manufacturing prohibited items).
I'm a gun lover (and own many), but I'd be a little concerned if these folks lived in my neighborhood.
I think the journalist’s sloppiness comes from ignorance.
Many of them have zero familiarity with the respectable traditions of responsible gun ownership in this country or the laws governing it. To them, possessing legally acquired firearms is just as much a crime as making illegal pipe bombs and hand grenades.
That’s the way they have been indoctrinated in school and attempts at providing some responsible gun education to redress the balance are always strenously resisted.