Yes, it does, but that is the modern interpetation. Mine also applies, and that is how, IMHO, the author meant it. Reed is a big supporter of the military and the partiots who make up the military.
"Simple-minded" has always been an insult in my world.
The definition I gave above came from the dictionary. And I didn't leave anything out.
As a regular Fred on Everything reader, I believe your interpretation of his use of "simpleminded" is correct. Like his father, Fred is a former Marine and a combat veteran. And I would think he looks favorably upon men who answer the call to arms without too much thought; that is what Southern men do.