Then someone should tell Assad to stop putting chemical weapons if forward military bases.
One might draw the 'wrong' conclusion from the presence of chemical weapons so close to front lines, rather than in specialized and highly protected facilities for the long term storage of such weapons. (I suppose that if one of our nuclear missiles was detonated, we could claim that it was actually the fault of 'rebels' who took the missile from us. We have a responsibility to protect our nuclear weapons from 'rebels' just as Syria has a responsibility to protect their chemical weapons from rebels.)
OTOH, I imagine that the Syrian government Information Minister has already got this scenario in his list of explanations as to why, if there ever confirmation of the use of chemical weapons, that it is not the responsibility of the government.