A bunch of claims made there with no evidence supplied to support any of them, and especially nothing linking domestic terrorism with run of the mill Trump supporters, although it's quite telling that one would make that conceptual leap, ostensibly to fuel some sense of personal grievance?

Based on first hand experience on the fringes of white supremacist organizations over the decades I'm totally unsurprised to hear law enforcement would have a hard time finding them in bulk as the percentage of people in the US who willingly harbor these kinds of views is a rounding error compared to the larger populace. It's actually pretty shocking how much trouble such a small group of people can cause on the rare occasion that they either muster the courage of their convictions and act on their beliefs or are goaded into action by law enforcement plants. In any case, trivializing these groups, either by dismissing their numbers or by trying to reframe them as mere "political opposition" is deeply stupid. These people are profoundly dangerous.