He argued for pacifism in a debate with Tom Woods. This in combination with his open borders immigration stance is surrender to the third world. Murphy is brilliant and perceptive but also profoundly evil, which makes him highly dangerous.
Discussion
I agree with your opposition to his pacificism. There is a time for peace, and a time for war. Open borders is also a bit utopian in the current world--or downright masochistic following Sheldon Richman's argument ("flood the system, let it burn"). But I also see the logic of that question as ultimately one of private property rights and freedom of association.
I am willing to say I disagree with him on these matters but I would not go so far as to call him "profoundly evil" and/or "dangerous."
Full disclosure: I know him personally, have since our college days, and he is far from evil or dangerous. He's brilliant, kind, and hilarious, even if we disagree on a few matters here and there.