I was forced to insult your intelligence in my last post by spelling out --- for the second time --- the real, actual difference between Rojava and a no fly zone.  The difference is so simple to grasp that I now have to question not your intelligence, but your honesty.  
You say that a safe zone requires defense with ground forces.  Yes, it does.  But in Rojava, the ground forces aren't facing hostile Russians.  As I stated before, the Russians are actually supporting the safe zone.  So there is the difference.  One involves the real risk of war with Russia, the other doesn't.  It is impossible to make it simpler.