If he has, there is no evidence for it. There is evidence that he has been fighting a war against violent jihadist extremists trying to topple his government, but that is a war. To conflate a war with “slaughtering his own people” is either profoundly disingenuous or intensely stupid. The Arab Spring protests were very quickly co-opted by violent extremist factions, and from that point onward Assad has been at war. There is no evidence that he has some weird, evil perversion that causes him to gratuitously barrel bombs children to get his rocks off, as your position insists that he does. There is evidence that he is fighting a war. The deaths in his nation are the result of war.