I have no doubt the rebels are just as willing to kill as Assad, but I doubt their ability to obtain and deliver CW by the means they appear to have been delivered, which is by air assault. I think you still neglect to factor in the fear and horror of a gas strike and the demoralization Assad hopes to inflict on his enemies as some see their families die a horrible and slow death, much more painful than a bomb blast. Also, Obama failed to back up his red line boast because he feared Iran would back away from the deal they were negotiating at the time, another reason that whole thing was a bad deal.