AMD may be not very competitive in mining when it's put against other GPUs, but this coin should be CPU-only, so if there exist a GPU that can mine it, it will be EXTREMELY efficient (few orders of magnitude better than the rest of miners - and that may be the explanation of these single entities that have loads of mining power).

So you say it's GPU resistant because it needs an amount of memory that no GPU has. Have you heard about Radeon Pro SSG?