Does it really matter what motivated him? Multiple premeditated murders pretty much should be a capital crime if you believe in the death penalty and life without parole if you don't.
I don't think this is a difficult case for the prosecutor. But, the logic of hate crime law is that there's something more anti-social and depraved about killing someone because of the race, religion, ethnicity, etc versus killing someone over a disagreement or a personal matter.
I think it matters because race-based violence/terrorism is something beyond just a mere murder. It's an assault on a group of people and the cosmopolitan multi-ethnic community we live in.