ottomans to not be acting according to The Quran?

It isn't so black and white. We can see instances where the Ottomans were certainly going by sharia while in other cases - especially in the final generations - that they were not. For example, the genocide of the Armenian people was completely unjustifiable beyond being an opportunity for the elites in Istanbul to "get rid of" the Armenians out east, as well as capitalizing on tribal/ethnic divisions in the empire. Last time I checked the Rasulullah SAWS didn't commit acts of genocide against innocent men, women, and children who had nothing to do with either the Russian government or insurgency groups, nor are there any sahih hadiths or verses in the Quran which justify marching men, women, and children into the middle of the desert to be shot.