Yes, genocides are emotional. Watching children being blown up is something that should upset you. That's actually happening in the real world.
Emotion isn't the only thing that should inform your decisions, but pretending like you shouldn't be upset at watching kids being blown up, or begging for their parents, or whatever else have you is just foolish.
People who go out and counter protest actively have given it more than a cursory thought. They know BLM isn't advocating for white genocide (okay, most of them understand this. There are some literal nazis/skin heads/white nationalists in the counter protesting groups that believe in The Great Replacement, but they believed this prior to BLM existing).
Yet they still go out and counter protest. It's not confusion at that point. You can't go up to an all lives matter reactionary and say "Hey! Did you know BLM doesn't actually want to murder all white people? Are you a fan of BLM now?" and actually expect any progress.