Who gives a shit. What happens in Syria has almost no impact on the global markets, let alone the lives of your average Westerner. Taken with the heavily Islamist nature of the rebels, why on earth would you intervene?
The moral hazard argument has been demolished time and time again. It doesn't make anyone more likely to use these weapons, nor does their use represent a security threat to Western interests.
Interventionists tend to be retarded, but principled interventionists are the worst of the bunch. "We should do it because It's the right thing to do!" If you hear that, run the hell away.