I'm not reading the whole tirade but chemical wmd should be a concern of everybody. The world decided on it in WW1 after so many suffered so horribly. It only leads to even greater chemical, then biological. You don't have to be a rocket scientist to see where that's going.
As far as the Nazis. They were after world domination and should have been stopped much sooner. We learned that in WW2. Those who don't know history are doomed to repeat it.
Assad can't do anything about world domination. Using your World War II issue, the Soviets were bent on World Donination too. They had spies all over the world. So our friend who isn't bent on world domination is better than our enemy bent on world domination.
Assad is no threat to us. He never was.