When he auditioned, Mary asked him, "What styles are you trained in?" He said, "Ballet. Modern. Tap, jazz. African." Then Nigel asked him if he had tapped and krumped at the same time, and he said he had.
The point is that he's trained, and not just a little bit trained.
The judges, especially Nigel, love to see HH people excel. Because of that, I'm guessing that's why there's more focus on his HH/Krump side over his other styles.
Anyway, I look forward to see Russell dancing.