The argument is "Well, he's not a right winger because he hated FOX News and the Weekly Standard, so that really makes him a radical Leftist" or it's "You can't call him a right-winger because he hated pretty much everybody."
Needless to say, Jon Chait kills this stupidity rather neatly.
So yes, he was a nutjob right-winger...and so far to the right he thought FOX and the Weekly Standard were just too soft on Obama, the Jews, the blacks, and everyone else he hates.
First, the "conventional political classification" is a rubric that accounts for extremists on the far right or left who abhor Democrats or Republicans. Ralph Nader has a lot of bad things to say about the Democratic Party, but that doesn't make him hard to classify on the left-right spectrum.
Second, a certain strand of conservative thought is comfortable with most of the tenets of Republican doctrine with the exception of free trade and, especially, Jews, Israel, and neoconservative influence. Pat Buchanan is the emblem of this brand of conservatism. Buchanan is generally a Republican partisan except for Jewish/Israeli/Middle Eastern issues where he takes strong exception. Von Brunn is pretty clearly a violent and more extreme adherent of Buchanan's basic worldview. That he would detest a neoconservative institution like the Standard isn't "complicating" or surprising at all.
Third, it's somewhat apparent from Von Brunn's writing that he did identify with the Republican Party on some basic partisan questions. He cheered conservatives for getting Dan Rather fired, believed Sarah Palin was unfairly hounded by the media, and so on. Indeed, if there's anything surprising and disturbing about Von Brunn's beliefs, it's that he identifies more closely with the Republican Party than I would have thought a radical white supremacist would. This may be a sign that the GOP has become more appealing to radical right-wingers than it once was, but it could also be an anomaly.
Comparing this guy to Markos "Daily Kos" Moulitsas or Keith Olbermann just because they dislike FOX News and criticize them openly is ridiculous. But hey, whatever helps these guys sleep at night.