You can't really evaluate how a black hole in our universe works by comparing it to a thought experiment of a universe containing just the black hole. There is a phenomenon called "frame dragging" in which the rotating black hole alters the spacetime around it through its rotation. However, in the reference frame of an observer rotating with the black hole, the rest of the universe is rotating, and from this observer's perspective, its rotation causes frame dragging in the opposite direction. The effect of the rest of the universe is that the black hole's frame dragging is partially cancelled out (and the net frame dragging decreases as one goes away from the black hole). So while the Mach principle does assert that a universe containing nothing but a rotating black hole would be indistinguishable from a universe containing nothing but a non-rotating black hole, that doesn't mean that a rotating black hole with our surrounding universe is indistinguishable from a non-rotating black hole with our surrounding universe.
Relativity says that the rules for what things do don't depend on the reference frame, but doesn't mean that reference frames can't differ in how things are affected by the rest of the universe. A car traveling at the same velocity as the Earth will experience different phenomena than a car traveling at a different velocity, but that's not because there are different physics operating on them, it's because the surrounding matter is interacting with them differently.