I think you're talking about the very same RBN based on the numbers you listed. He didn't say there was only metal, he said there was too much metal compared to other genres. In your list, Metal leads at 143, the next highest is at 81, and the third highest is at 42. That corresponds exactly to what he said.
There's way more non-Metal than Metal, though. To write off RBN as "the place assy metal goes to die" (and don't get me wrong, it does happen) and nothing else is so ridiculously shortsighted.