Not at all. The gas is not used as a first-order weapon, targeted against the civilians who died. The gas is a propaganda weapon, designed to whip up war fever against Assad, when Assad is on the verge of crushing the Sunnis who are allied with the Saudis and Qatar. See my map above.
Based on a map? How about Dictators do these things to put the fear of God into the people so they never rebel again especially when they have a big nuclear ally.