I've discovered your rants a few months ago, and it's good to see you back!
Well, I think I have an explanation for why authors write traitors as "Chaotic Evil" unless they're working for the Good Guys. As far as I can tell, that's how it's always played in real life. The average American doesn't know why Arnold Benedict defected to the British, they just know he's the "Big Bad". Most Americans don't know who Hans Speidel was, but he was a high ranking traitor in WWII.
Long story short, Hans chose the winning side, and he's now remembered as a hero. Arnold chose the losing side, and he died in poverty.
I'd say that traitors are always, or nearly always, going to be remembered because of which side they chose. Such simplistic characterization, however, is not a good idea for describing the traitor in the act. Too late at night to think of any really good examples, but I remember tossing a few books because the traitor just happened to be the guy with the goatee that the hero trusted unconditionally upon meeting him.