You can argue against someone's beliefs without using such unnecessary appeals against someone's "stunted mental faculty".
These people are cognitively impaired on a deep level. There's no argument against their beliefs, because their beliefs are a word salad of conspiracy theories and absolutely insane fantasy. Many of them should be in mental health facilities for treatment.
There's a lot of overlap with the survivalist/militia types. These people "plan" (such as their limited, stunted mental faculties permit) for apocalyptic scenarios and the destruction of our government. Many even view themselves in the role of a redeemer--they'll form the nucleus of the new society that will develop. And so on. There's just a whole strain of lunacy in this area.