So what of the airlines that are still flying over Syria, Iraq and Afghanistan?? Currently MOST airlines are still overflying these areas, can you guarantee that the rebels / freedom fighters in these areas don't have access to supplied / captured anti aircraft missiles??
It is all about risk analysis, remember 2 years ago Qantas was severely criticised for grounding the fleet after the South American Volcano ash cloud when all other airlines continued to fly.
Sometimes you get it right, other times evidence subsequently shows that you weren't risk adverse enough.