Having finally returned after his last defeat, Sombra had been prepared this time, and the Crystal Empire had fallen under his hooves, along with its inhabitants. Now, it was time for him to make sure his new slaves knew what their place was.
I know this is probably not plot driven, but I do not agree with Sombra's reasoning. Sure, you can have power and be "the winner", but that does not make you morally good. For example, the changelings wanted to enslave ponies for love, and ponies had to defend themselves. Did that make them the bad guys? No, since they didn't attack first and because changelings could find a peaceful solution, but they didn't want to. Second, well duuh, he left because he was abused. Some people don't want to fight their abusers, they just want to be far away from them.
This is getting good
I know this is probably not plot driven, but I do not agree with Sombra's reasoning. Sure, you can have power and be "the winner", but that does not make you morally good. For example, the changelings wanted to enslave ponies for love, and ponies had to defend themselves. Did that make them the bad guys? No, since they didn't attack first and because changelings could find a peaceful solution, but they didn't want to.
Second, well duuh, he left because he was abused. Some people don't want to fight their abusers, they just want to be far away from them.