Why does someone deploy chemical weapons on their own countrymen?
Because "countrymen" means
nothing in the ME. Tribe means everything. And the various countries are nothing more then a bunch of tribes throw together (and or divided by political boundaries, See: "Kurds".)
What we're seeing in Syria is not "Civil War", but Tribal War. Assad's Alawite tribe is and has been a minority in Syria,but retained power because he controlled the (originally Alawite) Army. Once Syrian tribal leaders saw what happened in Tunsia, Libya, Egypt, they said "Hey, we can take this guy." So some of the larger tribes banded together and away we go.
What we have now, is several tribes (as the FSA) and some AQ a-holes, fighting Assad's Alawite Army. The reason they are not doing better is each tribe is fighting for themselves, there is little to no coordination between tribes and you have AQ *expletive deleted*tards trying to bring about Jihad and Caliphate. If the FSA ever really got it's *expletive deleted* together Assad would be in serious trouble. However, if the Syrian Army ever gets it *expletive deleted* together the FSA would be in serious trouble.
So I can see both sides using WMD's on each other (and their "Allies"), keep in mind that some/most/all of these WMD's came from Saddam Hussien's Iraq.
Here's better insight about it, surprising from a Non-us source (again):
http://www.theguardian.com/commentisfree/2012/jul/25/syria-tribal-rivalries-shape-futureAnd yes, the only solution is an Asteroid. Hopefully, one side to the other has some nukes and set's those off. That will solve a helluva lot of problems.