The point of the tagline is simple, it is to question why "peace activists" are always against liberal Western Democracies like America and almost never complain about crimes committed by anti-American communists and fascists. It refers to Stalinists, Maoists, Ba'athists, and Pacifists. I don't see anything in there about liberals, democrats, leftists, libertarians, or most anyone else to the right of Dick Gephardt. It is not an attack on leftism, liberalism, socialism, or permissivity.
As far as I'm concerned, liberal Democrats who didn't oppose the war are probably basically decent people, and I think we can disagree with them respectfully. As long as people can recognize that Saddam Hussein and Joe Stalin and Che Guevara were terrible criminals, and it was good that America stood up to them and their ilk, they pass the test.
Arnold passes the tagline test with flying colors.