Neo Nazi group targets a power grid that supplies a populous with a concentration of 62% Black Americans. Since Black Americans make up < 16% of the U.S. population, I'd say that's a significantly dense population of Black Americans (If you add in other minority groups per the U.S. Census we're looking at 73.2% minority) 🤔
So there's your "evidence". Now, is it enough to charge and convict as a hate crime? Well, that's up to the judicial system, but I'd say they definitely have evidence. I'd also venture to say the FBI has additional evidence like audio/video recordings as well as digital evidence (social media/email transcripts, etc.)
I'd say there is more evidence this is racial motivated than serving chicken & waffles...feed the blacks food they love or take away their power during the winter. You decide.