Syria matters to Moscow not only because it has energy interests, military bases, and strong ties to the current government there. It matters also because Western interventions in the Middle East in the past fifteen years had consistently made the situation in the region worse. Basically, they have no plan for what happens after regime change (see Iraq and Libya for example). Power vacuum in the absense of strong institutions only creates fertile ground for groups like ISIS. Besides, this piece treats the "chemical attack" as if it's an established fact. Just to remind, Idlib province is controlled by rebel groups with strong ties to al Qaeda. They run health facilities in the province and all information about what had happened came from these people. When these groups fought in Eastern Aleppo, they themselves conducted chemical attacks. Should we take their words at face value? I don't think so.