An important Ashʿarī premise is that God’s action is not constrained by a law imposed by a superior authority in the way a creature's conduct might be. Disapproval measured only by human utility is therefore not a conclusive proof of intrinsic impossibility.
This stance does not automatically establish that an impossible obligation has actually been imposed; occurrence requires independent evidence. Nor does it erase all distinctions between divine action and human moral responsibility.
The immediate dispute concerns hypothetical permissibility, not an assertion that every conceivable case has occurred.