It's simple; the commission is not part of the African Union.
One of the members of the commission was my professor at the University of Ottawa in international law, and he was the chief justice at the Rwanda genocide tribunal. Obasanjo is the former president of Nigeria. He was not a member of the African Union. The commission is independent.
Then you have Professor Mahmood Mamdani, at Columbia, who is independent, and there's a lady from Senegal. The commission is independent, and therefore, that makes the commission credible.