Assume Assad used chlorine gas. Is it worth starting a war? Overthrowing Assad results in chaos. Thousands die. We might see genocide of one of the last Christian communities in the Mideast. Does it make us safer? Region more stable? How’d regime change in Iraq & Libya end up?
Iraq War was based on lies. Libya war was based on lies. Vietnam war was based on lies. So when the same old blood-soaked warmongers want to rush into war in Syria before an investigation can even start, it's time to disobey.