Final answer:
The provided details refer to the Dred Scott v. Sandford case and do not align with the Australian Mabo decision or an inquiry by Greg McIntyre.
Step-by-step explanation:
The information provided seems to relate to the Dred Scott v. Sandford case, not the Mabo decision, and concerns the questions the U.S. Supreme Court had to consider in 1856. Regarding the specific inquiry by Greg McIntyre, there is no clear historical context connecting him to the mentioned U.S. Supreme Court case. Therefore, given the mismatch of the information, it is not possible to determine which inquiry Greg McIntyre made in relation to the Mabo decision. The Mabo decision actually refers to a landmark case in Australia that recognized the land rights of the Meriam people, which might be unrelated to the provided details about the Dred Scott case.