The labels "left" and "right" being directly equivalent to "good" and "bad" or "selfless" and "greedy" may be overly simplistic. Suppose, for the sake of discussion, that crusader bunnypants really believes that the world will be a better place with his buddies (all completely trustworthy, in his eyes) running the whole show. By your arguement, he is completely justified in invading anybody who opposes his Utopian dream of universal freedom. That he's deranged, is a minor detail.
I tend to be extremely suspicious of anybody who claims "moral superiority". But that could be an overly simplistic abstraction on my part.