Any US military intervention in Syria, whether it be supporting Assad or the rebels, is basically open support for what can only be described as the "marginallylesser of two evils".
If Assad is Satan, and the rebel leader(s) is Beelzebub-- justifying support for the former because the latter used chemical weapons is sheer lunacy. Congrats, you just replaced one devil with another.
Seriously, let them all fucking kill each other. Been watching Arabs blow themselves up, blow opposing tribes up, blow jews up, and blow Americans up for 30+ years now and we obviously never fucking learn. Seriously, the entire populations of Syria, Iraq, Iran, Afghanistan, and all the rest of the middle eastern Islamist nations could disappear overnight and the world would be none the worse once we got someone to man the oil pumps. I seriously can't remember a single technology, medication, or Nobel prize ever emerging from one of these shitholes, at least in my lifetime. They contribute nothing to the world except for strife and war.