I tried to upload Dimebag Darrell (he had a separated project that archives his own recordings and compositons)

The page wasn't blacklisted, I added it and it got reject, and blacklisted.

In the EP The Hitz, there's two songs that are completely acoustic/non-metal, while three are groove/southern metal.

Nah, only one track is groove metal. Others are either some country stuff or some southern/groove rock. It's pretty much some leftover Dimebag's experimentations that the rights holder decided to publish as a posthumous release.